Rectal bleeding around menstruation?

Autumn

Hi!

I’m 18 and I have pretty irregular bowels, but in recent months it has evened out. During my senior year I had a couple instances in which I had pretty bad rectal bleeding during bowl movements. I had a colonoscopy over the summer and nothing abnormal was found. I never felt that it was hemorrhoids because I never had any pain or discomfort. After the colonoscopy I was fine again, but at the beginning of this school year I had the problem again. It’ll happen for a couple days usually before my period or after my period. Sometimes during my period. I am experiencing this again now, and was wondering if anyone else has something similar? I do use a menstrual cup but I don’t think that would have much of an effect?

Thanks