Jim
What led me back to the OS after four years was reduction in strength and flexion in my hip. (To the point where I couldn't complete a one-legged revolution on my bike - as an ex-triathlete ?? I think you will know what I mean

) I was diagnosed with extra bone growth and recommended extraction here in Dubai, but took a second opinion whilst on holiday in Australia, where I was made aware of the whole metal-on-metal scenario. I returned to Dubai and my OS here agreed that we should do more tests (bone scan, ultrasound, blood, etc). The only abnormality was a little fluid apparent on the ultrasound (which was an "afterthought' test).
Because there was no diagnostic sign of infection or reaction to metal, we decided to remove some trochanteric screws in case they were causing the inflammation/fluid build up. I had better range of motion immediately, but an unusually swollen leg. Finally the swelling reduced to a half-golf-ball sized lump on my thigh over the incision. After three months of patiently waiting for it to subside I went back to my OS who excised it then and there and found dead tissue. I was pretty excited to have a flat and semi-normal looking thigh again, but the lump was back within a day! (Later we established that the removal of screws left channels for the dead tissue to swish down and appear externally instead of being jammed in my hip joint.)
At this point I got my people at work (I work for Johnson & Johnson) involved and between them reviewing the symptoms (with some behind the scenes knowledge it seems) and my OS presenting my case and pathology at a hip conference fortunately being held in Europe around that time, we established that the only way forward was revision.
I guess the key point I would make is that my x-ray looked perfect in both position and fixation and I had no signs of infection or reaction despite very extensive tests. I really thought my muscles were dying ... I didn't have extreme pain, just discomfort and inability to do the stuff I loved.
The pathologist here still has not said there was anything unusual in the tissue that was taken from the first excision ... however the pathologist who was presenting at the conference in Europe has been studying this for a few years now and he was able to easily and conclusively recognize the reaction from my slides (seriously ... as I arrived at the hospital for the operation, my OS showed me a text that he literally just received from this guy saying yes definitely revision was the right course!). And for the record when they took the old hip out, it was surrounded in dead tissue.
It was hard for me to keep telling my OS that I thought we were missing something but I am so glad that we kept at it. One day he booked me in for an afternoon slot - 2 pm, with no-one after me so that we could just talk until we resolved it!!
I think what I went through is probably just a fraction of what you are going through; it sounds like you have a lot of pain.
Interesting that you also have a metal prosthesis. Has anyone tested for a metal reaction? (Have there been any cases with Zimmer implants of reaction?) I am sure at this point you just want a diagnosis ... would be great to rule this one out at least!
I am keeping my fingers crossed for you!