I just started taking microgestin this month. [I have taken it exactly when I was supposed to. I had sex three times this month as well, twice protected, once unprotected, and all three used the pull out method.] I also took plan B within 24 hours of having unprotected sex. I am now on the fourth placebo pill. I am experiencing brown, almost hard blood (it almost looks like a cow or chicken liver) about the size of a quarter, and then again the size of a dime. I thought this was odd, since it was not on the packaging. I've also been shedding a little bit of red blood, but none of this blood altogether was enough to soak a pad, as this is a very light period. Usually my period lasts 5 days and is very heavy the first three days.

I am wondering if this is because of the birth control, the plan B, or could I be pregnant?