My last period was on 3.26.13 it lasted five days. The next day I had unprotected sex, two days after I took Plan-B one step then four days later I had unprotected sex again (I know not the smartest idea ever; so please save the smart remarks && don't judge) Anywho two days after I had on and off brown discharge for about four days. My period was due on 4.23.13 and it is now a week late. I had sex throughout the month protected/unprotected. What could this be?