Biopsy-confirmed NLD-SFN + autonomic symptoms - What caused yours?

I’m hoping to hear from others with biopsy-confirmed NLD-SFN especially those with significant autonomic symptoms or whose NLD-SFN was eventually determined to be immune-mediated.

My skin punch biopsy confirmed NLD-SFN, but the underlying cause remains unclear. My neurologist has discussed idiopathic vs. autoimmune/immune-mediated, and I’m trying to determine what should come next diagnostically.

My symptoms include:

significant fatigue and reduced exercise tolerance
heat intolerance and excessive sweating
chronically low blood pressure/orthostatic-type symptoms
Raynaud’s
urinary dysfunction/altered bladder sensation
sexual/autonomic dysfunction
intermittent tingling/sensory symptoms
brain fog/cognitive fatigue
substantial day-to-day variability, sometimes with worsening after exertion

I also developed a positive ANA after previously testing ANA-negative, but rheumatologic testing so far has not established a specific systemic autoimmune disease. I have possible nail psoriasis and a history of longstanding iron deficiency, which has now been treated with IV iron and prescription Iron supplement.
I have significant spine issues. Cervical and lumbar imaging has shown degenerative changes, including disc disease/herniation with nerve involvement. I have experienced recurrent episodes of significant low-back pain with radiating hip/leg pain as well as persistent numbness of my left shin. I understand that structural spine disease can cause large-fiber/radicular symptoms and would not necessarily explain biopsy-confirmed NLD-SFN or the autonomic symptoms.
Q: However, I’m wondering whether others with NLD-SFN have also experienced significant or relatively early degenerative spine/disc problems, and whether their doctors considered the two related or completely separate conditions.

I’m particularly interested in people whose initial autoimmune/rheumatologic workup was unrevealing but whose NLD-SFN was eventually explained.

Q: What ultimately identified the cause of your NLD-SFN?

Q: Did autonomic testing (QSART, autonomic reflex testing, tilt table, sweat testing, etc.) help? Were there additional blood tests, antibodies, imaging, or other evaluations that proved important?

Q: Has anyone had both NLD-SFN/autonomic neuropathy and significant cervical or lumbar disc degeneration? Were they ultimately considered unrelated, or did your doctors identify an inflammatory, autoimmune, connective-tissue, or other condition that could help explain both?

Q: And for anyone evaluated at Mayo Clinic: did you see neuromuscular neurology, autonomic neurology, rheumatology, or another department? Who ultimately coordinated the investigation?

I’m not looking for an online diagnosis. I’m trying to understand what may still be missing from my workup and which specialist is best equipped to investigate it.