(((HUGS))) We've been there ourselves. Our DS has PDD with ADHD type symptoms as well and he's in an inclusion class. He went to a special preschool and came out worse than when he went in and I said never again.
First grade was really rough. He did so terrible that they were planning on sending him to a special school again because they said that he would never be able to take the state tests that he would have to take starting in 3rd grade. Since he was born in October I asked if they could keep him back in first grade again to give him another chance to catch up. It was the best thing. He had a better teacher that year and ever since then he's been doing better. He went from feeling like the dumbest kid in class to the smartest because he knew the work the 2nd time and it gave him confidence.
My DS has his own 1-1 para and that's been the key. Does your son have a para or could they give him one? His para redirects him when he goes off to la-la land when they're doing work he thinks is boring like math, and helps explain the work to him so he understands it. If it wasn't for the para, there's no way he would be in inclusion right now.
Unfortunately we also had to give our DS medication. I never wanted to, but I would do anything to keep him in his home school close to home instead of going on a school bus to a special school far away. He started off taking a tiny dose of Risperdal, which helped him calm down a little and stay in his seat (he used to just walk out!), and now he's just on Strattera to address the ADHD symptoms and it's working great.
I hope you find something that will help your DS!