Old blood between periods????

Hey y’all! Someone help me out here ... so I’ve been on the mini pill for about two years. I take it within the same 30 min window everyday. My last period was June 27-30, and it was pretty light. (I’ve never had horrible periods anyway but I also think the pill has lightened them) And then around July 12th I started noticing some brown discharge (like old blood) followed by some really dark blood. Nothing too crazy but enough to wear a little panty liner pad. It’s been going on pretty much every day since then, nothing too heavy.. but brown discharge / old darker blood. It’s almost time for my period again now.. so is it just old blood from my last period since it was so short? Or what?