Despite having people with all kinds of expertise on this forum, when I had a family member with TMJ there were maybe two others on the forum who had some experience with this problem.
We spent over a year and visited over a dozen doctors of different kinds (dentists, oral surgeons, “TMJ” specialist dentist,s chiropractors, and physical therapists - never made it to the neurologist, therapist, or physiologist that were recommended at various times). Paid thousands in treatments including expensive day and night appliances, muscle relaxants, NSAIDS, rounds of blood work, various x-rays (although never got an MRI or SCAN), props (foam roller, exercise ball, heel lifts, and back support pillows), stress reduction classes, and blenders to make liquid foods. I also lived on the internet googling and desperately searching for answers (advice - never believe medial information on Reddit - that is the worst).
The good news is that my family member is fine and can eat everything and lives without pain (there was about 9 months where they couldn’t open their mouth more than a finger’s width.)
What I know now is that for many TMJ (and it is really TMD - TMJ is the name of the joint) is a symptom of something else not the originating problem. In my family member’s case it was caused by an undiagnosed case of whiplash from a fall (with a slight concussion which was diagnosed). The jaw pain, limited mouth opening, and aura headaches came months after the fall, so the link was not obvious. The treatment was PT which strengthened and fixed neck and shoulder muscles. A very good PT (there had been several before her) figured it out by doing a complete evaluation of her body. The family member will continue to do exercises to keep these muscles in shape forever.
TMD is typically not covered by medical insurance companies because they don’t identify it as a medical condition (some dental plans do the same).
Given all this, my recommendation to you is to go to a TMJ Dentist as a start, because it sounds like the bite is causing the issue. We had better luck with general dentists who treat TMJ patients, instead of those affiliated with medical/dental schools and TMJ research. Call a dentist or orthodontist who you do respect and ask them who they recommend for their patients with jaw issues. In my cause, I had a dentist who said your issue is so bad he sent me not to the TMJ guy he usually recommends but instead the guy that that TMJ specialist sends his toughest cases to.
I will tell you that a pediatric dentist told me that he sees lots of TMD in his practice and stress is definitely a part of it.
GOOD LUCK to your DD - I hope you have a shorter journey than we did. Feel free to PM if you want.