I've been on birth control for over a year, since my last pregnancy. I use the 21 day pack continuously so I don't have a period. Day before I noticed a brown discharge and yesterday I was spotting, pinkish or streaks of blood with discharge. Also experiencing very mild cramps and headache but with terrible lower back pain (no nausea). I'm wondering if its possible to be pregnant? Last month I was I'll and used antibiotics (not sure if this could affect) then I missed a day before starting the new pack of pills so I'm flustered with what's happening.