I'm constantly afraid?

i'm always afraid and I don't know why :( I want to try out new things but it's so damn hard, and every little set back, any tiny thing that goes wrong like a person looks at me the wrong way and I'm bawling my eyes out. I'm a nervous wreck, constantly. What should I do? this isn't related to any one thing, I'm just always petrified that things are going to go wrong. Doctors haven't helped; neither has medication. If you have some words of comfort, I could surely use them right now. <3