hey, I can relate to some extent, I get the same way when I am in a class that's silent, its like a torture. I don't know if this is really applicable to your situation but I always found music helps, with headphones, also if you have both headphones in people will be dissuaded from coming to help you because it shows you are listening to music.
I may be being ignorant but what is S.A?
also want to add that you can try and use where you sit, for example corners are good, you can generally get along quietly sitting In the corner, try and affect a look of not wanting people to come up to you, like put your head down when working, if you get really unhappy just tell the teacher, say you get anxious sometimes and would be more comfortable on your own.