Bruxism Treatment Guy answers:

The muscles in your jaw have tightened up to go into pain and not let you use those muscles. To get rid of the pain you have to free up your jaw muscles to get rid of the stiffness in them and here’s how to free them up:
Put your fingers on your head so your thumbs are behind your ears. Press into the back of your jaw bone next to the skull and hold that pressure. After 30 seconds slowly raise your head until your neck is fully extended then open your mouth as far as you can. Release the pressure but hold your head and mouth like that for another 30 seconds.
For best results relax your body first by taking a deep breath and exhaling then remain this relaxed.
Plz consult a Doc