Hi, I started taking a course of antibiotics, I only had one tablet and then that same night I went out and drunk quite a substantial amount of alcohol and had unprotected sex. I am on Levlen ED, would the antibiotics have had an effect at that point on the pill? I stared bleeding very lightly on the last day of the brown pills, I am unsure if my period has come early or it may be something else. I was not due for my period for another 4 days.