Why do i have a horrible popping noise in the jaw when i open my mouth. and when i yawn a sharp pain shoot up the back of my neck and head?

Temporomandibular : Temporomandibular disorder arises when the TM joint, bones and muscles around them are affected. Symptoms usually are pain in the jaw and TM joint area especially with the opening/closing movement of the joint. Commonly precipitated by injury or tension in the surrounding muscle by teeth clenching kind of movements. Dentist take care of these problems; get it checked out.

TMJ: You have TMJ. See a dentist who may treat you him/herself or refer you to a TMJ specialist.