Pain can be puzzling. You know its there, but you or your doctor often cant pinpoint the cause-despite repeated tests. That doesnt mean the pain isnt real, and it doesnt mean you cant be treated. In fact, doctors and medical researchers in recent years have made significant advances in how they diagnose and treat chronic pain. "We know what works and what doesnt work," says Susheel Dua, M.D., staff associate in Cleveland Clinics Department of Pain Management. If you suffer from chronic pain, here are eight treatment options that may provide relief.