Ok so I have been on birth control (tri-sprintec) for 7 months now. Usually I start my period on the 3rd sugar pill at some point during that day. This month I started on the 4th which I know isn't that big of a change, but it's the first time it has started later so that freaked me out. What is actually weird though is that I had spotted in the morning so I put on a pad and tampon and then changed both about 4 hours later. I noticed I hadn't bled that much (practically nothing was on the tampon) then later when I took out the other tampon there was still only a little bit of brown blood on it. I didn't put another tampon in after that. I went to the bathroom about 2 hours later to see that I hadn't bled AT ALL. Then I started bleeding a little bit after that but not nearly as much as I usually do. Then it was really light again, then it got a little bit heavier. I went to the bathroom once and had a big clot come out like I normally do. And sometimes when I wipe the blood is a bright red, but seems to have a little bit of a mucusy substance in it. I have had pretty bad cramps, a little worse than usual. I am usually very heavy on the first day of my period. It is just really weird to me that my period is so light when I'm usually so heavy and that I started a day later than usual. I had sex once this month with a condom, but I just am worried that this could possibly be implantation bleeding? Or maybe just a change up in my period? What does everyone think?