Do I have social anxiety? If so, what could I do to get help?

Sounds like it. You should seek therapy.. There is a reason for your severe irrational fear of typical everyday social situations. I don't get nervous around crowds, I just get tired of them quite easily. When I was in high school, last year, my friends would be together... All the time... In large groups. I rarely attended myself with them, only because I do not like very large groups. I like to be alone, or with a friend.