I've suffered for about 6 years from iSFN. I can't type much because it's quite painful, but I feel I owe it to the community to report what has and hasn't worked in my experience. I hope it can help someone.

What (I think) works for me:
low carb diet
benfotiamine (300mg/d)
r-lipoic acid (150mg/d)
PEA Palmitoylethanolamide with luteolin 1260mg/d
Xyzal 1/day

Not sure:
Agmatine
vitamin d (but I'm deficient so I know I need it)
b12 (I'm was mildly deficient)
Lion's mane
MLS laser therapy at chiro
oxybutynin patch every 4 days- this is promising but too soon to know after 2 months

Didn't work for me:
ALCarnitine- gave me headaches, didn't help
Grape seed extract (headaches and doesn't work)
Topricin cream (doesn't do anything)
Turmeric
Inositol
L-arginine

Want to try if current doesn't work:
Tadalafil (Cialis) PDE5 inhibitor
Pirenzepine (oral- 25mg/day)

Nuclear option:
ketamine infusions

Good luck and hope you all are having a relatively low pain day : )