If you have a very aggressive type of pn, it is really not likely to be the ordinary "idiopathic" that most people on this board speak about.
"Idiopathic" pn is an indolent syndrome. It advances at a slow-moderate pace, and while some people have awful pain early, the pn doesn't usually march up their body this quickly.
I am suspicious that you might have a pn which can be found to have a cause.
While you say you have had many tests, it is not at all clear to me that you have ever looked at the charts I've posted on www.lizajane.org
, and compared the tests with what you've had to see if your work-up is as complete as your doctor claims.
I'd like to encourage you to take a look there. If you have an immune cause for your pn, you would benefit greatly from IVIG, and the whole thing might be ended and reversed. I assume you have had a really good work-up for B12 deficiency and gluten intolerance, but that's just an assumption. Many people have been told that they don't have these problems, but when they get a hold of their lab tests results and post up here, they find that people who are very expert can figure out that the doctors were not correct.
So, please, please, before you give up on ANYTHING, ask your doctor for copies of every single test that was run on you. Then make yourself a "chart" and share the results with us. This site is unusual in that it has people here who have made it their business to get well-educated on various types of neuropathies, who are more expert than most neurologists who are "generalists".