Hi Rachelle,
Have you had your 504 update meeting for next year yet, or is that done in the fall? If you can, I'd request a meeting now to address what you can add to the 504 to address the anxiety next year. You might also consider requesting an IEP under OHI for the PDD-NOS, with specific goals to help keep your ds organized and on track as he moves to the multiple classes in middle school.
Will the teachers all understand? Most likely not - that's just the nature of what we've encountered with our 2e kiddo. How large is the school your ds is at? Will he be with the same core group of students all day? Can you take him around ahead of time to meet teachers and see the classrooms? Do you think pairing him up with a buddy would help?
Our ds had a lot of anxiety going into middle school last year (he's not PDD-NOS, but he has LD and stress feeds into severe anxiety). One thing that helps our ds is when we can't eliminate all the anxiety a situation is going to produce, we can at least eliminate some and it helps. It sounds like handwriting is an issue for your ds (our ds has dysgraphia and dyspraxia) - is your ds using keyboard accommodations? If not, I'd consider working with him over the summer to move toward that and then perhaps if he feels like he's made some progress there it will be one less small little chunk of anxiety that he can avoid in the fall.
Our ds is very quiet and when teachers first meet him, all they know of him is that he's got dysgraphia etc (because we've told them ahead of time and it's in his file etc)... and that his handwriting looks like a 1st grader... and that the quality of what he writes is very elementary and simple. They don't see his brains and all his cool creative ideas - but I have to give most of his teachers a lot of credit in that once he's been in class and has had a chance to feel comfortable and contributes an idea here or there and the teachers get to know him better, most of them absolutely do realize how much smarter he is than he appears at first glance. I do feel though that having the accommodations set up to move him completely to keyboarding were *very* important in helping teachers see what he is capable of as well as important to have as he moved forward in school and his classmates' writing improved significantly. Our ds uses his laptop for *everything* in school, not just long writing assignments.
The other thing we did for our ds is specific to him but we switched him to a very small school. He could have stayed in the school he was in for middle school, but he wanted to change, so when we were looking at schools we purposely chose a small school both for that reason and also because we felt it would be easier for us to keep tabs and work with his teachers. I did a lot of work through the first half of the year going through his class assignments and locker etc at the end of the day with him just to keep him on track and make sure nothing got lost/forgotten/etc. which in turn helped keep his overall level of anxiety/stress down. If he'd continued at his public school he would have had oversight and help with this from the resource teacher. I don't know if that type of organizational skill is a challenge or worry for your ds but if they are, they are things that you can address in his 504.
That's all I can think of right now.... best wishes as you plan for next year!
polarbear