Yes, definitely he's had his ears checked thoroughly by two different docs, and one also checked the pressure.
I can't explain how I know it's involuntary, but I just know it is. My ped also agreed that it is involuntary. It's not a fast motion or even a long one, but I don't believe he can control it.
Yesterday I had him at my sister's house and he got very excited about seeing their dog and one of my nieces, and he shook his head several times in a very short amount of time. Once he settled in, he didn't do it for the rest of the visit, and never did it for the rest of the day. This morning he didn't do it at home but did it once at the grocery store when a woman talked to him while he was in the cart. So now I'm back to wondering if it's new situations, new people, etc. that trigger it.
He has never had any reactions to vax, but of course I can't help but wonder about it when MMR was the week prior. That said, he's walking now and that was not happening before vax.
Again, a million thanks to all of you for taking the time to write.