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Kimball~
Sorry to hear about your jaw pain.
I've been in the Dental Health field for 20+ years. I've also worked for a TMJ Specialist- that is a dentist who specializes in TMJ, which is Tempro Mandibular Joint; the joint that connects your jaw. This is what you are popping out of place when you clench & grind, resulting in the pain you are experiencing.
The best way to resolve this problem is to go to your dentist and have them make you a Nightguard. They will take impressions of your teeth so you will have a custom nightguard to fit your mouth. You wear it at night when you go to bed, and it prevents you from grinding and clenching. It SHOULD be most comfortable- if it isn't, then you should tell your dentist, and he/she can grind and/or adjust it to where it will fit you properly and be comfortable.