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!
"What is life? An illusion, a shadow, a story,
And the greatest good is little enough:
for all life is a dream, and dreams themselves are only dreams."
~ Pedro Calderon de la Barca, Life is a Dream