My last two stools have been bloody. I ve had a problem with diarrhea for a couple of years (about once a month, which I assumed was menstrual related or IBS), and recently, I ve been taking acidophilius for it--is this related to that? The blood is bright red. I m 18, if that means anything, and I ve been under a lot of stress lately. Otherwise, I ve been feeling fine (with no abdominal pain or anything).