That is a very sensible thing to do, unfortunately it does take a PN specialist to give you the best chance to find the culprit that's causing the damage to your small nerves.
I also had small fibre damage, i too was running on low b12 and i was found to be prediabetic, through a 3 hour Glucose Tolerance Test.
I hope someone will post you soon a name of a good Pn specialist in your domain.
good luck
Brian