Yep, I'm in this boat too.
Numbness for 3yrs in limbs, pain, muscle twitching, etc.
No idea how it started, it just did.
Tested for diabetes, and everything else.
After 3yrs of tests and a review of current and new symptoms each visit, I received a diagnosis of small fiber neuropathy in 2008. The Dr continued research, putting in new information as I experienced it. He'd give me a more refined diagnosis than the SFN. In the past year he stated I might have Lamberts Aeton, due to the amount of muscle pain. Still having pain, muscle and nerve. Still have the twitching all over. Since October of this year both arms feel tense, continually pulling muscles, etc. My Dr is looking into this, but still no diagnosis. He's one of the best Dr's in the area, at one of the best clinics in the region. There has been no shortage of research or tests on his part. But with Autoimmune conditions, the dern things are SO similar that it takes awhile for your body to put up a "flag" to show which direction the Dr needs to go next. I'm learning this, although I'm not fond of the pain, or the slowness of a sure diagnosis, but the most important thing is finding a Dr you can work with, that actually LISTENS to you. Each time I have a visit, we get closer to what I have. It's frustrating, especially the amount of pain(!) but eventually I'll get a diagnosis.