I agree with all previous posts, get rid of that idiot of a doctor and find another doctor that is willing to help you, ask to be reffered to a neuro that is very experienced with Neuropathy patients, don't just settle with a normal neuro, you need a neuro that is very experienced with PN, then you will have the best chance of finding out what is causing your troubles.
When i first found the PN board, one of the best bits of info i received was to find a good neuro that really knows about PN, so searched around and come across a Neuropathy Associaion in my state, so i emailed them asking for a recommendation for a good PN neuro and the director told me of 2 neuro's that he highly recommends, so that was good enough for me, so i asked my GP if he could give me a referral to see one of these neuro's, which were about 2 hours drive from were i live but i didn't care about that at all, but my GP said " there are plenty of neuro's locally, they are every bit as knowledgeable as these other neuros your asking to see in Melbourne, why travel all that far ? " its a long story but i held my ground and insisted to see one in Melbourne and he eventualy wrote out a referal for him.
This PN expert found the cause of my PN in his first load of tests, it was Prediabetes, these days i am nearly fully cured so it really pays to have the right doctor looking after you.
good luck
Brian