Interesting. I've been told I have small fibre neuropathy. I've been through all the hoops, consulted neurologists and others.
I did read, on Facebook of all places, an article about vitamin b12 deficiency. In the UK a blood test is done checking possible culprits for your symptoms. Mine was, mainly, an ice cold sole of left foot but both affected; sometimes burning, always tingling.Maddening. Relief when in bed at night. This article said that the standard NHS test for b12 is flawed, as it measures total b12. There is active and non active b12. Only active should be measured. To cut a long story short I challenged my GP, no joy. So, eventually I oaid for a private test on active b12. It was 30% below the lowest on normal range. My GP checked this then put me on 6 loading doses of b12 over 2 weeks. I've had to continue pushing but,with neurological issues, the Nice ( NHS overseeing body), guidelines state that the injections should then continue every other day until no further improvement. That's where I am. It's early days but I'm hopeful.
I've been tested for pernicious anaemia but it was negative. However it seems that test doesn't pick up all cases so I'm thinking about next stepson this. PA is main cause of b12 deficiency. Not the only one though. Proton Pump Inhibitors taken long term are a cause too( that's used for acid reflux). And others.
I'll update in a few weeks..

Prior to 1932 liver was the only treatment available for pernicious anaemia. Mow it's regular injections of b12.