This is a very old post - but still struggling with numerous conditions (42 yr old) which came on approx 2.5 yrs ago (NO COVID involvement) - Your basic synopsis above is a small fragment of my medical chart & I’d appreciate any more info you can help provide on the SFN! I was diagnosed with Mixed Connective Tissue Disease after a positive RNP test; confirmation of Hashimoto’s (long time under-active (or “actively being destroyed” ? thyroid); Fibromyalgia (which just appears to be the name of my widespread pain/discomfort issues; and the latest of which is the SFN (although the biopsy wasn’t 100% active SFN, Neuro said it’s definitely what’s happening & I’m just in beginning stages of it) - which is puzzling considering how frustrating/exhausting the symptoms I do have are!!! Feel free to private message me if needed! Thank you for your insights!!! Peaceful blessings headed your way!