Yesterday I was in the car and out of the blue my left jaw started hurting. It only hurts when I clench my teeth or open my mouth really wide though. I've been trying to search for some info on tmj but there's not too much out there. I have also experienced the locking of the jaw occasionally but not much. I also hear a slight grinding pop or something when I open my mouth on that side. I guess I need some answers as to what the symptoms of tmj actually are. Is the pain constant or just when chewing and yawning like me? This is the first time I have ever experienced the pain. Does the pain come and go or is it constant? Need info! Thanks!