And of course, I mentioned this whole scenario to a friend of mine who said that clearly DS has issues that other kids don't have, and we should consider medicating him for anxiety, and he has to learn how to deal with and get along with other people.
To me this is like saying "Just throw him in the river - he'll figure it out" about a child who can't swim. I personally had a really difficult time socially and emotionally in elementary school, and it would have made a world a difference to have a few adjustments.
I don't have any great suggestions other than possibly looking into a classroom switch if you really want to try everything before you pull out. Could you choose and talk to his teacher for next year? Would they be willing to let you supply curriculum for him or allow him to do an online program? Maybe if he could do Aleks online, he'd get some "quiet" time on his own during Math or something?
That's an incredibly difficult situation! Maybe make yourself a time line for improvement before you give up. Keep us posted!