Rudy, a simple trial on magnesium chloride or magnesium citrate for about a week(loading) will tell if its a problem related to an inability to relax muscles. I would use a compounded, pure solution made up by a local pharmacist. Most will make it without perservatives. Dr. Sherry Rogers talks at great lengths in many of her books about the importance of magnesium and what the lack of it causes. TMJ is just one of a raft of possibilities. Keep in mind there are other causes too but magnesium is a good thing to try and its simple and inexpensive.