Chronic pain makes life hell. It's a simple as that, and if I were in your position, I'd be doing everything I possibly could to find the cause of it and then eliminate it. I'm sure that's what you are doing, and it seems like you are in a game of exclusion. If you can't find out what is causing it, then at least find out what is NOT causing it.Does the pain feel more muscular or neural? Most of us have some gut feeling about our bodies (although with ESRD, those instincts can really go off track). Do you have any idea at all what it could be?