I'm a Los Angeles-based medical doctor who, for the past 25 years, has specialized in treating the LGBT community. I've witnessed the ravages of AIDS, the physical and psychological trauma of violent hate crimes, depression and suicide in a community specifically targeted for discrimination because of who they love.

And, after years of hard-fought battles against death, disease, violence and depression, I was convinced that we had turned a corner with successful HIV treatment, PrEP, anti-discrimination laws, hate-crime legislation and, most recently, marriage equality. I honestly believed that my generation (I'm a 55 year-old Baby Boomer) and my gay-pioneer predecessors had succeeded in creating a safer world for the next generation of LGBT young people. And then, Orlando.

As if the LGBT community didn't already have enough letters populating it's rather cumbersome acronym, after Orlando, we sadly need to add four more - PTSD.

PTSD stands for "post-traumatic stress disorder" - a condition that's triggered by a terrifying event, either by experiencing it or witnessing it. Symptoms may include recurrent, unwanted distressing memories of the traumatic event(s), feeling emotionally numb, hopelessness about the future, always being on guard for danger, insomnia, irritability and difficulty concentrating.

Orlando has shaken the LGBT community to its core. Nearly everyone I know is grieving, feeling outraged and mostly powerless. But why such an extreme reaction? Senseless mass killings have happened countless times before. So why the overwhelming sense of loss, pain, fear, despair and impotence in the LGBT community? Why this particular time?

We've endured an HIV plague, incessant bullying, state and religion-sanctioned discrimination, estrangement from families, beatings and hate crimes. And we survived. It got better for many of us. For a while. And then, Orlando - a new "9/11 moment" for the LGBT community.

The roots of this overwhelming wave of despair is both simple and insidious - it lies in this country's deeply ingrained fear of gay people and rampant unchecked homophobia leveraged for political, religious and financial gain. Most importantly, this cumulative abuse underlies a latent post-traumatic stress disorder (PTSD) that decades of mistreatment has inflicted on an LGBT community of citizens who have been pummeled and ravaged by hatred, shame, threats, disease and death.

A man walks into a gay bar with an AR-15 semi-automatic rifle. He kills 49 people and wounds 53 more. To America, it is yet another horrific mass gun shooting in a string of such atrocities in recent years. But to the LGBT community it is a direct blow to a nation of survivors.

The ensuing script is predictable. Shock, horror, social media in hyperdrive and wall-to-wall, 24/7 cable news coverage. The reading of names. The personal stories of victims, the survivors, their families and loved ones and of the courageous rescuers. "Thoughts and prayers" are offered by the usual public figures. An outpouring of grief, cries of "love over hate," mountains of flowers and candles, vigils and donations from well-wishers flood into Orlando.

All are simple, well-intentioned and often practical gestures, but they do not shed a ray of light on what really happened here. They are merely a well-learned, reflexive response to a society inured to self-inflicted horror and tragedy.

Next, the predictable finger-pointing game begins. Easy and well-deserved targets are the bought-off politicians who block sensible gun laws in exchange for campaign donations, unhinged religious homophobes and the much-reviled National Rifle Association (NRA) which markets for the billion dollar gun manufacturing industry and lobbies to block any gun legislation. They are all obviously complicit in this atrocity.

But they are not the underlying cause of the unusually extreme and profound despair that is gripping the direct and indirect LGBT victims of this killing spree - both young and old.

In years past, to be gay was an emotional, social or literal death sentence. And gay bars have traditionally been "safe spaces" from all of the hatred, violence and discrimination in communities outside their walls. But this time, like a deadly virus infecting a healthy cell, the hate made its way inside, with horrific and deadly consequences.

To the shock and surprise of many, me included, these old traumas still lurk just beneath the surface, waiting to be re-triggered by just the right catalyst. And Orlando was that perfect, if appalling, spark. To the LGBT community Orlando has torn off the scabs, reopened old sores and left an entire community feeling raw, angry, depressed and shattered. We had (erroneously) believed that we were well-healed by now. But these wounds never fully heal.

In the wake of Orlando, like traumatized military vets, we drop to the ground reflexively for cover and safety in fear that we are hearing those semi-automatic gunshots directed at us. And I've been literally overwhelmed by (heretofore emotionally stable) LGBT patients calling in with PTSD-like symptoms, myself included - despair, sleepless nights, hopelessness and fear have taken hold once again.

Freshly re-traumatized, the LGBT community is now faced with a choice - cower in the shadows overcome with this fear and despair OR become soldiers (yet again) with a unifying cause. If we rise up as we did with AIDS and our fight for equality, we will surely witness those feelings of despair dissipate. Better to fight - and maybe die - for a worthy cause than to be shot in a dark nightclub.

A Facebook blogger rightly and defiantly declared, "You can wound us, kill us, attack us, propose bills to take away our rights. You can judge us, bully us, project your fears on to us, you can censor us, ignore us, but you will never stop us. We are a community of survivors. We have battled persecution from our families, our schools and our governments. We lived through the holocaust, and then a plague. We have always dared to let our dreams reach beyond us. Every time we got knocked down, we got right back up. That is just what we do."

In spite of all this, I'm hopeful. You don't mess with a hardened LGBT community of survivors and get away with it. We fight back. We're tough, visible, organized, determined and powerful.

Orlando will hopefully reenergize a recently complacent LGBT community into action .It has marked the moment that our post-gay-marriage euphoria died and Cher-slapped us back into the reality that the fight for our civil rights must continue.

We're watching history unfold as everyone from the President to Hillary to multinational corporations to political leaders to billionaires like Bill Gates and Michael Bloomberg and Tim Cook to average citizens publicly express their disgust and their conviction to combat homophobia and to (finally) pass sensible gun legislation. The timing and sheer scale of this horrific carnage may finally make real change plausible - it's a Presidential election year and people are paying attention, and not only because "The Donald" is making reason and truth seem like rare virtues again.

We are outraged and we are mobilizing. All over the country and the world. It will be an epic battle which we will win. I'm 100% committed to getting an LGBT-friendly President in the White House, an LGBT-friendly Senate and three Supreme Court appointees who will shift the arc of history toward justice.

Now is the time to act. To stand up, to be counted, to come out, to vote, to march, to provoke, to organize, and to embrace one another as a cohesively diverse community once again. It's our second ACT-UP up moment in the last 30 years.

Stephen Colbert was spot on when, in his Monday night Late Show opening monologue, he eloquently noted that, "despair is a victory for hate." And LGBT citizens have not survived every indignity by wallowing in despair. Now is the time for love and laser-focused action. But Colbert rightly cautioned, "Let's remember that love is a verb, and to love means to do something."

Here are FIVE simple things that you can do to combat the "Orlando Syndrome":
1. Don't despair alone. Call your friends, call your Mom, call your doc, call your shrink.
2. Educate yourself about gun violence, homophobia and the preachers, politicians, media commentators who seek to harm us and those who support us
3. Vote for the LGBT-friendly candidate for the White House and for LGBT-friendly Senators
4. Email your elected representatives with your outrage at homophobia and lax gun laws
5. Be courageous. Be unafraid. Come out. Publicly show affection for those you love. And always remember that "Silence = Death." So "act up, fight back, fight hate!"