I wish I knew more resources to direct you to, but I don't. I do think that the GI problems are somehow related to Autism, though. There does seem to be a very strong statistical correlation. Most people I've talked to or heard from with autism spectrum disorders have some very serious GI problems. I've suffered from them too, though I've never needed to be hospitalized.
One thing I've been curious about is whether or not stress and anxiety might be one of the contributing factors. It probably doesn't explain everything, though, because I used to have problems ever since I was a kid. And I don't think I was under significant stress at that time.
Well, whatever the case, I hope others can help out more. I'm curious too to see if anyone has any good research to share.
_________________
I don't suffer from insanity. I enjoy every minute of it.