What are your physical manifestations of social anxiety?

I’m in upper-year undergrad and most of my classes have a 15-20% participation mark. I usually get by without doing any participating because the classes were always so large, it was difficult to discern who did and didn’t speak. But upper year classes are much smaller, professors know you by name.

Since I’m forced to speak publicly. (because all of us are “a little shy and dislike speaking in class”, I’ve stopped asking for accommodations) On the rare occasion I can rehearse a response that I feel might not lead to public ridicule, I often find myself holding my breath whilst talking (an enormous feat, idk where I developed the habit) and often find myself getting tunnel vision whilst speaking, sometimes I feel like I might faint, which is quite scary. It’s the worst when I can’t just say my piece and go, but peers and professors want to start a discourse with me. I may seriously faint one day, which would be mortifying and add to my fear.