This is becoming a mantra in the medical community. I don't necessarily disagree with it,
BUT (<-- Big "BUT"

) there's a difference between not believing
everything you read and not believing
anything you read.
Medicine knows a lot, and is learning more every day. But still, with all our technology, there is still more that medicine
doesn't know than it
does know. And research into what medicine doesn't know is more often driven by economic$ than by altruism; there is more money to be made on treatments and drugs that are patentable than on cures and natural supplements that aren't patentable.
A lot of people on this site are helping themselves with supplements and by sharing the information they glean here and elsewhere. Doctors often aren't aware of it because it is not (yet) taught in medical schools, and they are
also taught to dismiss/reject anything that is
not taught in medical schools. One of the major tenets of the
Hippocratic Oath all doctors take is "
Do no harm." I'm not a doctor, but I've taken that tenet one step further in my own journey; "
If it can't hurt to try it, then it can't hurt to try it," which presumes that whatever it is I'm going to try
can't hurt me to try.

Ironically, this usually means discussing it with my doctors (who are more open-minded than many). It's difficult for anyone to say unequivocally that something
will help you, but there may be some things that are worth a try. Reading the
Sub-Forum and
Sticky Threads in the
Peripheral Neuropathy forum are good places to get ideas for things that might help; not just supplements, but medications, tests, questions for your doctor(s), and any/all manner of useful tips & information.
It beats me how the new PCP could make such pronouncements and disagree with the neuro, but...
http://neurotalk.psychcentral.com/post718933-5.html
Googling:
MCTD peripheral neuropathy suggests that PN (and Trigeminal Neuropathy) can be symptoms of MCTD, so that may answer part of your question. You might google it yourself and see what you think based on your history & symptoms. Another tenet of medicine is,
If you can't treat the disease, treat the symptom(s), which is what many of us with "idiopathic" PN are doing. As the disclaimer goes:
Individual results may vary.
We're all on our own journeys here; this is a good place to visit and revisit,
Doc