Daisy,
Braces can cause TMJ, several on this board are proof of that. Others, braces has helped their TMJ.
It is a very complex subject, one nobody really understands. The locking, popping, headaches are TMJ related. Consider yourself very lucky if there is not much pain involved. As for what to do about it, I will leave that alone. If I had it to do over again, I would have done nothing.
Elaine