From what I understand, TMJ can be triggerred by stress. I tend to grind my teeth in my sleep when I'm stressed, and my dentist said that could lead to TMJ. If I start grinding again, she's going to have to make me a mouth guard to keep the damage to my teeth & jaw to a minimum.
My mom had TMJ when she was in her 20s and had to have surgery- she had her jaw displaced and then wired shut for a few weeks. I don't mean to scare you, but it was a really bad case. Unfortunately I don't remember all the details; I was about 7 or so at the time.
When my dad started developing symptoms in his mid-20s also, he got braces.
Good luck with your appointment! You've already been through a lot, so hopefully your treatment will be less invasive.