I'm not diagnosed either, but have been having buzzing sensations for months now. Mine usually are a warning of a new flare coming on, though sometimes I get an isolated buzz in a foot or finger for no apparent reason.
I don't know if they're Lhermittes or not though, because mine can go on for hours and sometimes days, no matter what position my head and neck are in.
I'm not sure why they occur. They're just weird though. I told my PCP yesterday that my husband keeps telling me this is all in my head, but that some of these symptoms, like the Buzz, are so far-fetched that my limited imagination could not have possibly dreamed them up.
Good luck to you. I hope you get some answers to your health problems soon. I know how aggravating it can be to know something is seriously wrong, but all the tests show normal.