Feel your pain and I'm there with you. Mine would get 'locked' shut at night so I couldn't eat or drink. Turns out I was 1 mm from the top of my
jaw bone breaking through my skull. I found a neuromuscular orthodontist who has done wonders. I just have another three years to slowly bring every
tooth to the correct place for my muscles to be in their 'happy, relaxed position'.
On topic: the girl needs to get help, it never gets better on its own