Sometimes when i yawn widely, the muscles from my neck to my jaws lock up and i can't swallow from 1-7 hours. what should i do when this happens?

Avoid over opening: Although this needs proper evaluation, it sounds as if you are sublimating (popping out of the joint space). If so, place a fist under your lower jaw when you have to yawn and prevent your jaw from over-opening. If this does not help, surgical alteration of the joint (eminectomy) can be performed if the problem gets worse. If the problem is a displaced disc, this can be repositioned.