Is this panic/anxiety attacks? And what do I do to correct problem?

I worry about anything/everything esp. when I'm with a group of people---"Are they talking about me? They're probably saying bad things about me. They don't like me." Then I get all worried and they notice I get upset and then I definately think that they think I'm crazy or something. I get all nervous and my heart races. I worry more and all kinds of stuff keep repeating in my mind---never positive thoughts always negative. They have got worse since I'm doing a Colon Cleanse but I am addicted to caffeine--I have to have Mtn. Dew or I really feel awful--I know I need to completely stop drinking pop. I always am scared of being judged by others. I find stuff to worry about. It is driving me crazy--sometimes I just want to give up. And I get so mad at myself for letting everything bother me. Someone please help.