Dark blood and brown discharge

Hey guys! So I’m on birth control and have been for the last year. I take it everyday like I’m supposed to even within the same hour each day. In addition my partner also pulls out every time but we don’t use a condom. I had my period 2 weeks ago but when I went to the bathroom today, there was blood/ brown discharge. I know that this can be an early sign of pregnancy so I started freaking out a bit. Do I have anything to worry about or is it just leftover blood from my last period? The only reason I’m so concerned is because I’ve never had blood other than during my period week before.