What do you do if you feel suicidal and don't have anyone to tell?

I've been "plagued" with this problem for at least a year now, and it seems to be getting progressively worse. I feel like I have lost the ability to communicate with people. Sure, I can make small talk about the weather and stuff like that, but I feel like I've lost my openness and humor with people. I figure I am changing and learning new things about myself, but this is getting ridiculous because it is affecting my social life drastically.

Whenever I get into a conversation with someone, either on the phone or in person, I become flustered. I have a problem with eye contact and I become very hot and sometimes I turn red in the face. Worst of all, my mind seems to be blank all the time and I can't get past small talk (even with my friends). I put a lot of pressure on myself when it comes to maintaining eye contact and continuing a conversation, but this pressure seems to fluster me more. I also seem to notice long pauses in conversation which I interpret as moments of awkwardness.

I realize that I have nothing to prove to anyone, but this problem still persists. I used to be very social before and now I am not. So what must I do to get by this? I figure, I'll just deal with it and it will go away, but it's been going on for too long. What must I do?

I look at my reflection time and time again, and I ask myself: "Is that me?" At some point during the past 3 years or so of my life (throughout which there has been no specific traumas I can name, recall, or otherwise), I have lost the ability to recognise my own reflection. Looking at recent photographs, I often have to take a few moments to recognise myself then. Older photographs are even harder to recognise, especially if I was unaware of the photo being taken. Do I suffer from some kind of neurological pattern-matching disorder? It reminds me of dissociative identity disorder, but I have no referential 'other identity(ies)' to work this from. Is this a common problem for 16-year-olds like myself, or am I going insane faster than I thought?