This link might help regarding methods of treatment: Temporomandibular Joint (TMJ) Syndrome Causes, Symptoms and Treatment on eMedicineHealth.com
Depending on the severity, as well as your insurance company, coverage will differ. Oral surgeon consulatations, x-rays, and MRIs are practically mandatory across the board.
Also, in most cases, Botox will not alleviate any pain. In fact, some people have reported increased levels of pain following injectable relief for TMJ, as it can aggravate the condition, based upon how bad the existing condition is.