P.M.
Your use of the term "self stimming" suggests to me you have educated yourself about autism. Other than simply not wanting to believe it's possible, do you have a good reason to believe that's not your son's problem? There's a boy I have interacted with for years in my religious community who exhibits similar characteristics.
If you haven't looked into the possibllillity yet, here is a good informational resource:
http://autism.about.com/od/whatisautism/a/symptoms.htm
My hopes are with you, K., that this is not what's developing in your little boy. But if it is, the sooner you can get appropriate help for him, the better off he'll be.