Sorry to hear that you're in this state. I'm in my 30s too and with SFN. It started in my hands and feet and then with some autonomic symptoms and then expanded to my face and trunk, and now it's all over. The cause is still not known, but autoimmunity is suspected even though all tests have turned up negative.

I still suspect alcohol myself, since I wasn't an alcoholic but I did binge drink and that can cause PN/SFN. I stopped drinking as soon as I knew alcohol was a neurotoxin and noticed the correlation between a night of drinking and my symptoms. I haven't touched it for a year or so now.

Stress and exhaustion are huge trigger for me, so I try my best to reduce both, getting plenty of sleep and avoiding stress.

Diet is another trigger. With some unfortunate lapses, I've been on a paleo diet or the autoimmune protocol, and it has made a huge difference. In fact, for a while I didn't even eat fruit and so it was more of a paleo ketogenic diet, and I'm thinking of going back into full ketosis again. Here's a link to a paleo autoimmune protocol, which is really based on the idea that there is intestinal permeability or leaky gut and inflammation and the idea is to reduce it: http://www.thepaleomom.com/the-autoimmune-protocol.

It may be worth trying this cream: NOW vitamin D cream. I continue to find great relief.

I also use a number of supplements always looking to finding ones with the fewest fillers and additives. I do use B12, benfotiamine, D, NAC, digestive enzymes, C, folate and some others.

I wish you good luck in finding the cause and healing. It's not a fool's errand; people do find the cause at times. it's certainly not impossible and definitely worth the effort, however frustrating it can be.