When I was first dealing with the neuropathy about a year ago, I had some breathing issues. Same deal-exertion would wind me quickly. Felt like air hunger. Stairs were awful.

I ended up getting a complete cardio workup-echo, stress echo, ekg, 3 day heart monitor...I couldn't even complete the low key stress test haha.

But-my heart was completely fine, and there didn't appear to be an issue with my lungs.

Eventually the breathing issue went away. I get it a bit sometimes still-but not often, and only when I am low on sleep and high on stress, and also when it is damp and humid. For me, I think last summer the breathing issue was caused by extended stress (wasn't even diagnosed with SFN at that point-so I was doctor hopping and getting millions of tests) and lack of rest. I had pretty wicked insomnia off and on. I also wasn't eating as well, because I had lost my appetite.

Once the insomnia got sorted out, my breathing seemed to follow suit, but it took some time. My breathing does get a bit weird also on humid days-I have allergies, pretty bad dust mite ones-so year round. Damp days bring them out, and I have a harder time allergy wise on those days (breathing, tired, pressure around eyes).

I completely agree that with your history of autoimmune and autonomic symptoms that you should get a cardio work up-at the very lest to rule out anything in that area. I'm really glad I got one done even with everything coming back normal. I hope yours turns out to be something allergy related and nothing organ related. Lots of luck.