My experience is with doing child-care for some special need kids (although personally I think all children have special needs) and I can also relate to your son's behavior. I didn't have that many episodes when I was his age but I did have some.

It's important that he has an outlet, drawing or reading. He needs a place he can go mentally and/or physically that is safe and comforting. I was nanny for a 5 y.o. who curled up in a milk crate when he was distressed, I could get him out of the milk crate by reading to him. It could be a stuffed toy, a certain book, activity or even something like apple juice whatever brings him back. Having a routine is also really comforting and important.

Having another thing to take care of might seem overwhelming but there is also a lot to be said for animal therapy. I can't tell you how many times I was able to keep it together because my animal depended on me. I have a cousin with Ausberger's who is the same age as your son. He doesn't relate to people naturally but shows incredible affection towards his cat. He calls her his "angel". I think he adores her because she doesn't have the emotional demands on him that people do.

Whether he is up or down it might make him feel better to know that you recognize it. I'm twenty-eight and if I had the option of sitting on my mom's lap every time I feel depressed I would. Ask him how he feels and if he can communicate it, repeat what he said and ask him what would make him feel better. If he's not verbal in an episode he might be able to communicate with a sticker chart later.

Extreme emotions can give us tunnel vision, it might make him see the larger picture if he can use stickers to represent different emotions and see them all together.