thoughts on this? TMI

my boyfriend finished inside me saturday (day after my period ended & day before I started my new pack of bc pills) obviously with it being so close to my period ending, there was some leftover blood and some that ended up on a panty liner which is not unusual for me. well fast forward today Monday, I have slight cramps for some reason when I just went to the bathroom and wiped there was this reddish brown pink colored discharge… Is that leftover blood? I’m just confused on what’s going on