I also was popular in HS even getting nominated to homecomming Court. I found the same difficulties in college although I believe I have an underlying mood problem as well I face anxieties all the time. Once you make a good staple of friends you will care a little less about others. It is tough, going from a school in which you know everyone and can interact with everyone to a school that you know noone. I'm there with you, only 1 semester left for me.