Help please!

Ok so I'm all new to the emergency contraception. So about 2 weeks ago I had my period. It came as normal and on time. After that week I was on my last day and I had sex with my boyfriend. I had a feeling that the condom my have slipped or broke so I went ahead and took plan b to be safe. Almost a week after taking it I notice there was a little blood. Is this normal? I haven't takin any other medication, been eating right and feeling normal.