I had never heard of it before then. That particular doctor told me that it came from "living in hell for 24 years." I was shocked, since he knew very little about my life. LONG story there, so I won't share it, but it SEEMS that [at least in his eyes] that stress and anxiety is one cause. I really don't know. I do know that leaving that world behind did not really help with the pain and aches. It has escalated over the years, as it does with anyone. I finally reached the point that I simply had to have some medical help; thus all the prescriptions that did not work, and finally the tramadol. I was prescribed the tramadol for back pain, but it does nothing at all for that.