I actually have TMJ, so that triggered a lot of my migraines in the past. I also used to clench my jaw when I was sleeping as well as when I was awake. This was mostly because those times were high stress times. The more stress I was feeling, the worse my jaw pains/migraines. I noticed that I would wake up in the middle of the night or in the mornings and my head would be pounding and/or my whole face would be hurting.
I hope you feel better soon!