Why does my jaw keep locking up?

See a specialist.: You have a problem with the jaw joint(s) commonly called tmj. The best thing to do is see a dentist specially trained to treat this type of problem. My recommendation is to google "trudenta dentists" enter your zip code and see if one is near enough to you to go to. If not, google TMJ specialist and see what is available.

Displaced cartilage: The problem is most likely the result of a piece of cartilage in the TMJ slipping out of its normal position and preventing the mandible (lower jaw) from moving properly. The first thing to do is stop chewing gum or very hard foods to keep from irritating it and get it examined by a dentist with experience in TMJ treatments. The range of possible treatments is large so accurate diagnosis is a must.