I am on birth control and I take it as directed, and never miss a pill. I had my period M-F last week like normal. Then I started the yellow pill again Sunday like I'm supposed to. Today, I went to the bathroom and there was blackish blood in my pants. Not much, just a little. What could that mean?

It is likely old blood left from your period. Many women will experience some similar spotting of dark blood after a period ends. Sometimes birth control pills may cause irregular spotting or bleeding on occasion as well.