Endometriosis can cause bowel adhesions, and guts that don’t move well can lay the groundwork for small intestinal bowel overgrowth. Irritated muscles from endo can spasm and spasming muscles can cause diarrhea too. It’s a whole cluster and it will be easier to work on with this info.

Menstrual cycle around the 20th, ovulation around the 10th ish? If menstrual cycle impacting that much, maybe endometriosis. Certainly worth a GI consult- excellent data. 10/10, will make a doctors life easier.