Whenever i chew gummi candy, eat starburst, or eat apples, my jaw will lock and it becomes very painful. why?

Muscle spasm, joint: You probably have something wrong with your temporomandibular joint like a dislocated disk or a problem with your muscles that attach to your jaw. You need to see a dentist familiar with joint/jaw problems or an oral & maxillofacial surgeon. In the mean time stop chewing things that make your jaw hurt especially like chewy and hard foods.