The fact that you've stuck it out w/all the testing 'should'have gotten at least ONE doc's curiousity up? I sure hope so!
At least you KNOW what IT isn't for now. Start looking? [Just in case?] at other possible docs, and be SURE you get copies of all these tests 'for your records'! You'd be surprised what all you can learn, tho not necessarily discern from it all. Boggles the brain.
Another set of nerve conduction studies should 'likely be set up' for 3-6 months later to 'assess' any changes. DUH? Next and equally important should be blood work! Expect a barrage of that, and just be sure to hydrate well for the 3 days before the test, when you start 'fasting' [which is usual']. Between those two? They could IF smart zero in on a good problem and equally more important a good solution! 's - j