i am having the same problem only i had my wisdom teeth removed months ago any explanation
I had this problem. It came and went for years. I'd wake up one morning unable to open my mouth more than an inch, it'd go on several days then all of a sudden I was back to normal until it happened again. I forget if it was TMJ or not, but I finally went to a dentist about it and he said because all four of my wisdom teeth were growing horizontally into the molars in front of them underneath the gumline, that if I had them removed (or at the very least the upper ones removed), I would stop having the jaw lock up on me. It's been 6 years and I haven't once had it happen since the upper wisdom teeth came out. Good luck.