I am on birth control and had unprotected sex with my boyfriend (mistake on our part we're usually careful). It was during my menstruation week but I hadn't started bleeding yet. The next morning (Saturday) I had spotting which is typical for my cycle. We went to the Pharmacy and got Plan B. Later that day my period started but it has yet to stop. I started taking my birth control pills again on Monday and I am still bleeding today (Wednesday). This is very uncommon for me. Is this due to taking Plan B?