I went through a very severe TMJ-like experience for many months. I could hardly talk, it was so bad - my bite was off kilter, I had a bit of popping in the jaw joint on one side, my tongue seemed swollen, and it all just ached. It all started when I got a new job, and I came to the conclusion that I was clenching my teeth during the day while I was concentrating on work. I was sure I wasn't grinding my teeth at night, and I was resistant to plunk down thousands for a splint.
What helped was professional massage concentrating on my face and under my jaw. I would massage myself during the day and pretty much just poke and prod at my face on the drive home from work. The Dr gave me some Valium and Vicodin, and with the massage, I was able to stop the cycle of the spasms and tightness. BTW, the dentist suggested I have a glass of wine to relax. That may have been part of the problem, that I was drinking quite a lot of wine, and drinking can make muscle tension worse.
Hope this helps -
It is difficult to qualify the effect of stress on the body, whether it be your back,stomach,or TMJ area. There is no question that stress plays a part in muscular soreness. There have been many studies on the effect of stress and back problems. In the same vain the muscles that open and close your jaw are attached to the TMJ as it would be with any other joint in your body. Not all TMJ difficulties are stress related but for sure there are many that are.