The inside of my head vibrates whenever I yawn or gag, sometimes it is so intense that I shed tears. What could be the cause?

Have you been to the doctor? That’s who you should be asking..

Kinda broken.

When you say inside of your head, does it locate any place in particular?

Could be temperomandibular joint syndrome (or TMJ) for short. The vibrating head is not a listed symptom, but I think it could just be your way of saying, my head hurts when I yawn or gag. Yet another possibility is trigeminal neuralgia, which would also fit your (albeit limited) description. The only real way to know is to go to a doctor for a thorough evaluation.