Histamine issues- need to aid the body of getting rid excess estrogen. People suggest DAO enzyme.

I also read that some people take Flonase or an allergy pill everyday.

Lichen sclerosis. I developed this in my 20s. Always in the week before my cycle. My mother developed it after menopause. So while it is autoimmune, hormonal changes can trigger a flair. There is prescription cream that manages it well.