How to deal with pain in jaw muscle or submandibular joint?

Two diff. Things: If the pain is from the jaw muscle under your cheek that could be from the parotid gland under it, if the pain is from the joint TMJ , treatments varies from a simple night guard to surgery, see you's dentist to determine the cause of the pain and treat it.

A few things: Depends on symptoms, and cause of symptoms. 3 signs of TMJ dysfunction: joint noises, joint pain & limited oral opening. Self treat with soft diet, jaw exercises, massage, heat/cold, OTC pain meds. A splint or physical therapy would be next. Occasionally muscle relaxants, biofeedback. Xrays are done for diagnosis. Surgery usually reserved for serious symptoms not responsive to other treatments.