Wow, dude, you sound a lot like me. I have SFN, idiopathic as it is. I have had about 40 different tests, 2 DNA scans, 6 brain MRI's, and on and on. No cause is known. It now causes pain over about 98% of my body surface. I cannot open a water bottle because the ridges on the cap feels like holding a handful of razor blades and squeezing. I cannot drive a manual transmission because the constant shifting puts pressure on my palm and thus the razor blade pain as well as more foot pain in my feet because of the constant use of your feet pushing in the clutch. Drying off with a towel is like rubbing yourself down with 40 grit sandpaper. Swinging a hammer, riding a bike, swinging a golf club, opening jars, many little everyday things we take for granted are now very painful and limiting for me to do. Without heavy meds, I cannot get out of bed and even put my feet on the floor.

A punch test by your neuro doc will tell him if its Small Fiber Neuropathy, though it sounds like what you've got. If they don't find the cause and your blood tests all look normal, then the next thing is to see how far its progression goes. Some folks have it only in their feet and/or hands, fewer still have it full body like I do. If its full body SFN, you may be stuck with pain management as your treatment. Though its got its side effects, its better than the alternatives, and you can learn to live a fairly normal life. Just keep open communication with your neuro docs, take initiative with your health. Don't be fooled by woo woo medicine either.

Take care and best of luck. :-)