I have tmj, I woke up this morning with jaw pain that runs to my back. I rub my back and it feels so sore. What's going on?

TMJ pain to upper ba. Your TMJ involves more than your jaw. The joint on each side of your skull is in the temporal bone, which attaches to other bones and muscles including ones in your neck and back. There's also a small bone under your jaw, hyoid, with muscles to the t as well as to the shoulder blade (omohyoid muscle). See your dentist or another TMJ specialist.
TMD. The term TMJ is rarely used unless there is documented true disease in the jaw joint. The term tmd (temporo-mandibular disorder) is more appropriate and in ENT practice most patients come to the specialist with otalgia or ear pain. Once the ear canal and ear drum are considered normal, the most common cause of pain at the side of the face is masticatory muscle spasm.
Neck and TMJ issues. Put your elbow on the table with you hand up. Put your lower jaw on your hand so your jaw is supported by the table. Then open your mouth be rotating your head up and back. Every time you move your jaw these muscles move to keep your head still, but they are always in function. They must also be addressed as part of the total treatment and may be part of the cause of your pain/problem.
Seems related. Severe TMJ muscle spasms can extend to neck, shoulders, arm and back. Make sure your TMJ problem is managed by a TMJ expert. Any dentist can be a TMJ expert with the proper training and experience. Most commonly, oral surgeons, prosthodontists, and orofacial pain specialists. Ask your MD, your dentist and your dental society for referrals.
Pain affects area. When one part of the system is out of balance it affects other structures. Your head and neck muscles can affect or be affected by the tm joint for any number of reasons such as your bite or posture. You may be clenching or grinding your teeth. Your dentist will manage your pain first, then evaluate and treat the deeper causes.