I know how frustrated you must feel right now, and I'm very sorry you are going through this. It sounds like you have a very severe case.
May I ask how old you are? I feel the body can heal in miraculous ways if given the right tools to do so. Sometimes the most simple of adjustments can give the body exactly what it needs to heal. The pain you are feeling is just the body's over-compensation for the jaw issue itself.
Keep looking into other therapies you can incorporate into your routine
I think an osteopath would be a great start for sure. Have you considered trying craniosacral therapy? Also, I have continued to hear great things about myofascial release therapy. I am in the works of finding a therapist in my area who focuses on this. I am very hopeful. Have you heard of prolotherapy by chance?
Sometimes the very simple things can help as well. Try moist heat on your jaw area and neck/shoulders a few times per day. You can also alternate heat and cold therapy. perhaps try a muscle rub on the areas of muscle that are very intensely sore. Have you given light stretches a try? Just keep at it and remember to not eat anything chewy. Give that jaw a rest and perhaps your muscles can take a tiny break every now and then.
Please work to make appointments with some specialists in your area. If you can find one that can figure out the source of your problem and what the past dentist did to you and correct it then that would be wonderful.
I appreciate the suggestion. I may reach out to him for feedback. Are you taking anything for the muscle pain? Have you noticed any nerve pain whatsoever? Sorry for the long post and numerous questions!