Possible pregnancy or infection.

Patient: I recieved my period about 4 days late and when I was sure it had ended I began having a brown mucus-like discharge. When I was sure it had gone away I had unprotected sex and he did ejaculate inside of me. The discharge started again followed by a couple days of bleeding immediately after intercourse. I’m on birth control, but I messed up on the second week with the active pills and didn’t take the whole pack as instructed. (missing days, 5 days in a row on the second week) I continued until I finished the pack, though. How possible is it that I might be pregnant? And if not, what else might it be?