I have right jaw pain at cheekbone hurts to bite down & open mouth wide hurts to touch no cavities , what's causing it?

Muscle spasm/strain: If the teeth are fine, and no possibility of a fracture in the jawbone then this sounds like a muscle issue. Most often related to clenching from stress or overuse from chewing. Your closing(&some opening) muscles are subject to spasm and strain. Hot moist compresses on the outside of the mouth and warm water soaks inside will help. Ibuprofen 400-600 mg 4 times /day for 5-7 days. Soft diet.

TMD: It is possible you have TMJ related pain . Possible muscle splinting (spasm) similar to a "charlie horse" although pain in cheek bone is a bit unusual. Unless you are confusing which anatomical area hurts. For acute muscle spasm take anti-inflammatory meds such as advil (ibuprofen) or alieve . And go see a dentist for a definitive diagnosis.

TMJ: It sounds like muscular pain or referred pain from trigger points. This can be due to the way your teeth bite together. It could be from a whiiplash injury.It could be a sinus infection. There could be an abscessed tooth that is interfering with your bite. You need to get an exam to determine a cause.