Thanks, I didn't realize this had ever posted so I just now saw your replies.  
I guess I don't know a lot about 504 plans, accommodations could be made based just on anxiety?  I've been reluctant to take him to a psychologist again-- I've done that in the past and of course he wouldn't speak to her so no progress was made.  It just stressed him out so much just to be there that I gave up on it.  
I'd love to have something official though.  Because it seems to be a problem at the beginning of each school year- a battle to get each teacher to understand that he's not just being rude or refusing to participate.