It happens every month with me too, I do believe there is a relationship between hormones changing and UC. All my flares were during my menses, my first flare was during my pregnancy, I was dignosed with UC right after delivering my baby. also my migraines headache are hormones related.
Yes, my main thing though is that I hope that it is not uc related or a flare. I mean that I think digestive issues during your period and before are actually just normal and something that will pass. Not a flare up of uc.
I agree with the hormone connection and uc flares but the diarrhea with your period I am hoping/thinking is just the way it is for lots of ladies,,, uc or not.