I had a similar experience once and the pain was so bad when chewing that I thought for sure my dentist was missing a cavity or fracture! My whole jaw on lower right side hurt even while eating soft foods. After all testing, bite tests, and xray revealed nothing, I was given a mouthguard to wear for several weeks as the dentist insisted I was probably clenching and grinding my teeth. I laughed and rebuffed such a suggestion or that grinding/clenching could cause this kind of pain.
Well, after 2 weeks of wearing that thing, I was out of pain and have been ever since! He explained that it can cause severe pain and that the ligaments of the teeth become inflamed and sore with extreme pain for some people.
I used a cheap, temporary guard made by my dentist to try so that we didn't spend a lot of money on one in case that wasn't the problem. You can also get them at drugstores at a fairly decent price. Good luck!!