Brown Discharge?!

My period started around 20 days ago, but it lasted for about 12 or 13 and then I started just having brown discharge. I am on the pill (sometimes I forget and take it as soon as I remember--which has only happened maybe 3 or 4 times out of my current pack) and I am sexually active. I had sex a few days before my period and I started having sex again around the 8th day of my period because my periods only last 7 days. We use condoms if we want it to last awhile and he always pulls out.