You might want to look into TMJ disorder. You might be either grinding your teeth or clenching your jaw in your sleep. This can cause a lot of discomfort in your jaw, depending on how severe it is. This will also cause headaches. I clench my own teeth in my sleep at times. My dentist did not see any wear on my teeth, so it isn't at a point where it's severe and they said that wearing a nightguard would really only help if I were wearing away at my teeth. Unfortunately it can be a tricky thing to figure out a way to solve, but perhaps this can at least be an idea of what is causing what you feel.