My jaw tends to low up when yawning. what can i do?

Likey TMJ disorder: It sounds like you are experiencing temporomadibular joint disorder. This disorder can come and go throughout a lifetime or become constant. Signs of tmd are pain in the jaw, ear aches, headaches, popping and clicking, and can cause your jaw to lock. This condition is usually brought on by stress, however can develop overtime if your dental bite is not properly aligned. I suggest a prosthodontist.