Good evening, I think you are having problem with your joint called TMJ (Temporomandibular Joint). No need to worry. It happens when this joint get overworked. This overwork happens unconsciously. Follow this instruction for few days. You may get over from this problem. 1. Prevent Wide opening of your mouth. (It Happens during Yawning,  Lock it with grip your nose and cheeks with your finger. It will help you to prevent wide opening of your mouth.) 2. Avoid side to side movement of your lower jaw. It cause more damage to your joint. 3. Stop sleeping with left and right side to avoid unnecessary movement of joint. 3. Avoid eating Hard food like Waffers. 4. Strictly follow this instruction for 15 days you may get relief.