Fear of failure may be. Mistakes.

Whenever I am alone all is good but whenever I am with people (even with my father, class ,friends - simply people who have critized me in past or somebody who is superior than me) I start obbessive thinking like ... am I look good, am I walk perfectly, have I done it without mistakes. Also so I can't make more friends and I have friends that are not superior than me. I like company of friends who have the same pesonality. I have fear of public speaking too, I avoid to being in social situation and one day my Sir said to me: stand up and count students.. Than my heat was beating too fast I roughly counted and anyhow ran away without noticed. All that...due to obbessive thinking I can't do my best and loss confident.Yet I have improved little bit as condition is not so svere but sometimes something happen and back to the same point. Please suggest something.