Where am I going? Lost...?

I am losing my confidence. I don't know why. I just look at people when I'm talking to them and imagine all the things they're thinking about me.... that I'm ugly and awkward looking and trying too hard. I had to do a presentation for class and I ****** it up so badly, my hands were shaking. My friends aren't inviting me out as much as they used to, and I keep blaming myself and treating social occasions as if they are a performance that I have to pass to prove I'm not boring. This is crazy **** and I don't know where it's coming from, but I feel so lost. In high school I had lots of friends and was known as the daring one who pulled the pranks on the teachers and said the things no-one else would. Now I'm just fading because I can't stop thinking about how I come across. Urgh so bloody frustrating, the more I notice it, the worse it gets.