This has been going on for months. Maybe even years, I'm honestly not sure because I've gotten used to it, but it suddenly got much worse during the past few days. My jaw will pop and click loudly when I move it from side to side and it will often lock, usually when I try to yawn. I'm not able to fully open my mouth when it does, and will have to close it, 'wiggle' my jaw a bit left and right before finally being able to open my mouth. There's no pain involved, but it's pretty annoying.