Feeling weird being around people .....question?

Please don't say rude stuff, but I don't like to be around people. I sometimes feel misplaced and don't wanna be there. I don't wanna talk to anything. I get somewhat nervous I just feel weird and sometimes I'll feel itchy or something. I don't like being around people that I don't know.. Sometimes I'll ditch friends cuz there bring someone new with them that and so on. I don't know..It's confusing... how do I get over it?.. what is it? Thanks so much for your help :)