--there are a lot of serological tests that should be done, if only to rule out a batch of potential causes.

This clinical application paper by Dr. Latov and ques Diagnostics is pretty comprehensive:

http://www.questdiagnostics.com/test...ripheralNeurop

A lot of us also use the Liza Jane spreadsheets, which weer designed to be about as comprehensive a listing of tests for neurological symptoms that a lot of minds could come up with:

www.lizajane.org

A word about your celiac comments--almost anyone with neurologic symptoms of unknown cause should get a celiac panel. I don't know what you meant by your 'poop' profile, but celiac does not always present with eliminative disturbances.