You know, starkiller, I had, and somewhat still have, the same problems you face. For me, the cause is far too complex to mention here, but it turned into a point where I chose to seek professional help, and I think you should do the same. Doooon't just jump into conclusions, like saying "oh I have social anxiety and depression and this and that", and don't go jumping into drugs. Seek a professional therapist first. A cognitive psychological therapy can help most cases without the use of any drugs, and belive me, you don't wanna take those things that mess up with your nervous system, specially for yourself, as you described phisical symptoms you have that are caused merely by your own state of mind.

You know what I've changed in my mind so I would stop worrying too much about myself on social situations and about my life?

a) I don't give a fuck to what people think about me. If they say it out loud, I'll sue their asses, so there.
b) I only hang out with people I want to, at the places I want to. I've learned to say "no" without feeling bad.
c) This won' apply for everyone, but: I feel more and more that I'm really asexual. I don't really care about screwing hot girls every day.
d) Apreciate real friendships over popularity or "being cool". That goes well with (a) and (b).
And... e) Alcohool is not that bad!

Apart from the obvious advice - seeking professional assistance - I'd like to know a bit more about yourself so I can advice you on some other things.

1- How confortable do you feel at your job?

2- Do all social situations make you unconfortable?

3- Do you live all by yourself? (a mere yes or no is ok, some people don't wanna say too much about their private life)