You say you have good teeth, then does your
jaw click
when you bite or chew? You may have TMJ, which can cause nasty
jaw pain. I have it.
Muscle relaxers are usually the best treatment and massage of the jaw muscles outside of the jaw under your ears. Also, place your tongue at the bottom of your mouth flat. Try to pin the tip of your tongue to your bottom teeth. Then try to open your mouth straight without your jaw popping out of place.