I am 26 and I have had a regular period since i started having one, every 28 days, every now and then maybe 1 day early or late. But last week my boyfriend and I were being intimate and I started bleeding and didn't think much of it. Then today I started bleeding again but it almost seems like a full strength period, but I'm not due to have my "regular" period until next Thursday. I took a pregnancy test and it was negative. But I'm wondering if there could be an underlying problem or if I'm just having my monthly visit way early than I should. Any Advice?