I had unprotected sex and took Plan B the morning after. Then about 2 weeks later got my period which lasted about 5 to 6 days. The flow was normal. Then exactly 28 days later I got my period again. This time it started out very light and then got heavier the next day and went on as normal. It lasted about 6 days. Then, 2 days later after it stopped, I had a very dark brown/red discharge only once..then the discharge was very light but I'm assuming this was what was left over from the sudden one. I'm thinking this was because of Plan B because I know it can mess up your cycle. But I've heard of people confusing vaginal bleeding to their period. I have had absolutely no symptoms of pregnancy and I'm pretty sure that what i got was my period due to some cramping etc.