Hi, Thanks for posting this query on healthcaremagic. The chances of pregnancy on last day of period and three days later are extremely low and if you are on pills they are almost absent. This is not due to pregnancy but more likely due to infection, or irregular bleeding caused by pills, hormone changes or non cancerous cervical growths like polyps. I suggest that you check to see if the discharge has an offensive smell. If yes, then it is more likely to be an infection. Also see a gynecologist and get yourself examined for infection and other local causes like lesions of the cervix. Further treatment will depend upon cause. Hope I was able to help you. Thanks for using Health Care Magic. I would be happy to answer any further queries. Have a nice day. Dr. Madhuri Bagde Consultant Obstetrician and Gynecologist