Hey Budgirl,
If it looks like a duck, quacks like a duck and walks like a duck, it's most likely a....duck!
You were applying pressure to your chin, you yawned, it went crunch...most likely some form of trauma to the joint. You likely forced the head of the condyle (the ball part of the joint attached to the lower jaw) off the supporting disc ( which lies between the ball and the socket) or stretched some of the ligaments surrounding the joint. This results in something like a sprain and some local inflammation and discomfort. Treat it like a sprain for now.
TMJ or TMD is a neuromuscular response to repeated stress to the joint and the supporting muscles which leads to some spasticity to the muscles of mastication and then a failure to properly syncronize these muscles in normal joint function. TMJ is NOT the actual injury to the joint but a response to that injury or excessive stress.
This does not rule out an ear infection but the motion that immediately resulted in the internal noise, pain and residual soreness is most likely a form of joint trauma that has lead to acute tenderness to the affected side(s).
Anti-inflammatory drugs such as Ibuprofen, Naproxen or even Aspirin can be helpful if you are able to take them. Moist heat to the joint can help. Avoid chewing gum, large bites of food, sleeping on your side or stomach...anything that can strain the joint.
Can you get a TMJ condition from this? Yes. Immediate treatment will probably result in a full recovery if you have not had joint issues in the past. Certainly, if the pain persists, see your dentist. No one dental specialty has a "lock" on the treatment of TM joints. I would start with my regular dentist first and then be referred as appropriate.
As long as you can hold your regulator in your mouth, I don't see any reason to not dive. Other posts referring to bite guards and SeaCure mouthpieces may become appropriate if resolution is not achieved by early treatment of this injury.
Laurence Stein, DDS