--normal EMG's or nerve conduction studies do not rule out all kinds of neuropathy, as those tests are too gross to measure problems with the smaller, unmyelinated fibers; to gauge those one would need very special testing, such as qualitative sensory testing, sudomotor axon reflex testing, or a skin biopsy (the current gold standard).

I tend to think,, though, from what you're saying, this sounds somewhat systemic, though, and investigating along the lines Mrs. D mentions is likely a good idea. I'd also be tested for gluten sensitivity/celiac if you haven't already been titred up for that.