Update:

Went to other specialists and ignored the neurologists.

Found out:

Have fat soluble vitamin deficiency, including vitamin A deficiency, despite adequate dietary intake, which apparently was discovered as early as 2016, but no one told me about it (until now).

Got biopsies for SFN from dermatology, waiting on results. GI did genetic tests, so on top of previous positive biopsy and blood test, I also have gene for celiac. Was told I'd be referred to neurologist on east coast who deals with celiac-related neurological sx, if neurological symptoms are determined to be celiac-related.