This never ever used to happen to me but about 3 months ago my jaw randomly locked while i was chewing gum. When got it to unlock it popped and ever since that day it locked i have been having problems with it popping and its soooo annoying and uncomfortable D: Things i do that could be the problem is when im really tired which is usually 99% of the time, i grind my teeth at night really bad, but i have done that forever so why all of a sudden it decides to lock!?!?!?! please help.