Hi Robyn @boltz7555, I'm not a doctor but unfortunately I think it may be a real thing for some women. Hoping other women with small fiber neuropathy can share their experience with you. While we wait to hear from other members, here are a few references I found.

"Can menstrual cycle affect nerves?
New findings suggest not only that PMS is tied to decreased nerve activity each month, but also that those with extreme symptoms may have a permanently depressed nervous system. For some women premenstrual syndrome (PMS) is a minor monthly annoyance, but for others, more severe symptoms seriously disrupt their lives." --- Bad PMS May Mean A Depressed Nervous System - ScienceDaily: https://www.sciencedaily.com/releases/2007/12/071219202940.htm

Menstrual cycle-related exacerbation of disease: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3107848/