Bleeding mid cycle. Help?

I normally have about a 28 day cycle and I'm on a pill but my last period was weird to. Anyways yesterday I started cramping and had brown and pink bleeding and only had a panty liner in all day but only had like two drops of it by end of day but saw a lot more when wiping. My period isn't suppose to start tell the 15th and it's only the 5th today and I'm not really seeing anymore bleeding today when I wipe. I been on the pill for almost a year now and it's never done anything like this before and I have never really been good with take the pill on time. Today I no longer am cramping but I have no idea if it was just spotting, implantation bleeding, or a side effect of the pill even tho I been on it for a while now and it's never done that. Could someone help?