Classroom/Presentation Anxiety at University

I'm asking for advice on how to deal with my anxiety in classrooms. I've had the same problem since I was a kid, I have always been extremely quiet, anxious and socially awkward when it comes to a classroom environment, however outside of a classroom I'm almost a different person. As a whole I'm generally a very social person, I'm a very party type person; I love having social gatherings, partying and I'm even a nightclub bartender who serves potentially hundreds of people a night with no problem. When it comes to classrooms, any conversation with peers feels forced and awkward and my heart will be raised and hands sweating however, outside of classrooms I don't care for if people judge me. It bothers me so much that I've recently had an ungraded Group Presentation, (I had done a lot of work on the Presentation and on other requirements for the assignment) but I had decided not to go in for because the thought of public speaking infront of the class gave me so much anxiety I couldn't sleep. I don't understand my own mind being able to serve say 100 people in one night at work with no problem, but not able to present infront of 20 people in a classroom.