I Have Had Muscle Pain And A Weak Feeling In

I have had muscle pain and a weak feeling in my legs for several years now. I was put on tramadol and had relief from the pain and later put on cymbalta 60 mg. I was told it blocked the pain so I have had relief from it also. One doctor said my atp level was low. I have been tested for neuropathy but was told I didn't have that. The last few days the muscle pain seems to be coming back. My doctor has tested for everything he can think of. Any ideas? YYYY@YYYY