Not a doctor, and I don't know if this is scientifically true (proven, I mean), but it seems like people on the spectrum can be more sensitive to the parkinson's-ish effects that certain drugs (like Risperdal) can have.
I.e. people with parkinsonism (the effects of Parkinson's, not that the drug causes Parkinson's) can have dystonia, where, basically, muscles end up pulling against each other in an unnatural way. Also, people with parkinsonism can have trouble moving, so that they move slowly, or even freeze like a statue. It is my understanding that those effects normally don't happen with anti-psychotics unless high doses are used, though. And, again, not a doctor, so all this could be completely unrelated to the pain and paralysis you're having. But you could look up "dystonia" and "parkinsonism" and see if they seem to fit.