Welcome to the board, Doglover222. Sorry you're going through this with your companion.
I remembered a thread that started out as a discussion of Masticatory Muscle Myositis and ended up with a diagnosis of compressed cervical nerves. The thread is here if you want to look at it:
www.pets.ca/forum/showthread.php?t=87917 Not sure if it'll be helpful, but it does point out that these sorts of symptoms can be hard to diagnose.
Is there, by any chance, a veterinary chiropractor in your area? I'm thinking that if it
is some sort of nerve compression, maybe treating for it would help resolve the issue, even if you don't have a definite diagnosis. It wouldn't help something like MMM, but t's not likely to hurt your boy, regardless, and maybe it would help.