Hi. I don't know for sure your headache is due to tmj, but it certainly could be. It is one of the side effects from tmj. I get tension headaches on occasion, because the muscles surrounding my tmj get so overworked with all the pt and exercises I'm doing. My physical therapist said it's normal and the best thing to do is to try to relax for a few hours. And, if possible, take a muscle relaxer. Of course, trying to find a few hours during the day to relax is impossible, but I try, and it does help.
Good luck,
Tandy