Oh, I can answer that chewing question easily

The two quickest ways to calm the nervous system are oral stimulation (chewing everything) and genital stimulation (masturbating). Both of those behaviors are extremely common with SPD.

Chewing things, especially his hands, could be one of two different reasons, or possibly even both.

Quote:Mouthing, especially of the hands tends to occur for one of several reasons. First, they may be very sensory overloaded and trying to organize themself. If you see this behavior incrase when it is noisy or busy that may be the case. Second, they may have very poor oral and/ or hand awareness, what's called decreased tactile discrimination skills. In that case they may be seeking input to try to stimulate themselves. It's kind of like being wrapped in a winter coat and gloves or having novocaine in your mouth, it's hard to feel things. Since the mouth, hands and genitals have the most sensory receptors, those are the most sensitive areas of the body and tend to be the most frequently sought out to provide increased input.

I found that somewhere when I was googling it for myself one day, lost the source x3