Most neurologists are clueless as to the proper care & treatment of PN.
Idiopathic is too often labeled when the doc is bluffing, clueless, and wants you to gop away.
Listen to Glenn.
Go to Lizajane.org to see all the tests that should be done.
Get yourself a neuro who is a specialist in PN & does research.
Johns Hopkins, The Jack Miller Center, Cornell-Weill, & Mayo Clinic (my last choice), are good places to find a good neuro.