If I need to go somewhere with lots of people I wake that morning feeling shakey, nervous etc just a very strange feeling. After the event I either feel like no one liked me or I feel I've said the wrong thing and go over it and over it in my head and imagining they think I'm this very strange person. I appear very "normal" and put together to look at.
I hope that makes sense. I also feel that way when there is nowhere I need to be so not just social situations but it increases massively in social situations.