Blood

I had sex (protected) last night and was fine today I woke up and did my normal thing then went for a run at about 11 (I haven’t ran in about a month) when I got home I went to the bathroom and there was blood (or at least red coloring) in my normal discharge. I just got off my period Sunday (like yesterday was my first day off my period). What could this mean (I feel like I’ve had this happen before I just want to check