old blood?

i ended my period sunday and started a different type(same kind((as far as i know)) just a different name) sunday as well. i put my finger inside of me and like swirled around and this was what came out... is it old blood or is it from the BC or what? it didn't have a smell from what i could tell.

i also took a preg test the day i got my period because i was stressing myself late and it was negative. later that night i started my period(it had clots like usual)

i also had sex last night around this time (august 30 8:30pm)