Hi, Thanks for posting in HCM. I understand your concern. There are several reasons why you could be having brown spotting after intercourse. First, it is possible that you are starting your period as it is due nearby. This is of course the most common cause of such spotting. Since you have been engaged in unprotected sex during fertile period with missing of birth control pill, it is also possible that you have conceived. After conception, few of them experience a small amount of bleeding or spotting following implantation. Also, such spotting could have caused due to infection and hence beware of any signs of infection like pain, unusual secretions or continued bleeding. If any of such symptoms occurs, seek medical advise right away. Right now, if you miss your period, then get urine pregnancy test done and consult Gynecologist for further management. Hope the information provided would be helpful. All the best.