When I was 30. (32 yrs ago) I didn't know what it was. I assumed it was from standing all day long in my job.

When I finally had some extensive thyroid tests including a scan 15 yrs later...and given thyroid hormone treatment, and my feet woke up and the terrible pain finally subsided ..bingo.
I had my answer. (I also had severe carpal tunnel especially during my pregnancy).

When I started my investigations into alternative supplement use for preventive medicine over 10 yrs ago, I found the TONS of information on PubMed. One only has to look there and be motivated to do so. I have training in chemistry, biology, biochemistry, drugs, pathology, etc and can read and understand most of what I find.

I started on the internet in 1998 and found another health board where Rose was posting. She taught me about B12. While learning THAT, I discovered the biochemistry of methylation, and expanded to other systems.
Then I met jcc and learned about gluten intolerance, and malabsorption. Then Glenn joined us, and he has a mind for the tests. He was very aggressive himself for getting all the tests needed, so he helps here with that aspect. He is also a very good communicator! Liza Jane made the spread sheets for recording those tests logically so doctors could easily use them.

Each time one does a keyword search on the net, things come up. It is sort of like going down a branch of a tree and visiting many leaves.

The way science works today is so specialized, we lose sight of the whole. I found interesting researchers in my searches which gave me hope. Since I have extensive experience with drugs and patients (I see everything) I put 2 and 2 together.
25 years ago it was rare to see PN in younger people. Only the very old had it. Now we see that changing considerably.

Today the new trends are for mitochondrial support. This is for aging, and also to understand damage from drugs, toxins and vaccines. Dr. Bruce Ames has done enormous work in this area.
You can Google him.

So my perspective is two fold.... my professional work, and my personal suffering.

Many people on this forum have been here (we moved from another place a while back) as a group for a long time. We learn from each other, and collectively appear to be "experts"

The reason doctors don't "know"? Well it is complex and they have to know so much, one cannot expect them to follow all the research on everything! (besides the drug industry has taught doctors to only use their drugs---to make $$. There is no incentive to heal people, just keep them drugged and feeling no pain). Not all can be healed. Severe damage from poor cardiovascular issues, dead neurons, amyoidosis, and genetic failures over time, take a serious toll. Those patients need drugs to remain comfortable. But not ALL PNs are that extreme. The peripheral nervous system is capable of regenerating, and doctors patients see ARE taught this. They just don't know how to enable that healing, YET.