Hi pingpongpie, Welcome.
Many many people are prescribed gabapentin for PN pain.
There are dozens of causes of PN, and depending on the source, 30-40% or more cases are idiopathic (unknown or no known cause).
Innaccurate blood tests happen, but I think the chance of it happening -- for whatever reasons -- 13 or more times is pretty unlikely.
There is a
Peripheral Neuropathy Forum here.
There you will find a wealth of information on causes, testing, information on what may cause innaccurate readings, and much much more.
Doc
PS: I don't know
anyone to whom PN is a friend!