Night splints done by regular dentists often cause more harm than good. TMJ is very misunderstood and extremely tricky to treat. Many people who don't get the help of a truly informed modern nm dentist who's done a ton of post grad work and has a proven history of healing TMJD sadly either don't get better or get worse from the wrong treatments.
Reserch the best nm dentist in your state and get there soon. These issues are much easier to treat at the beginning.
Best of luck!