His smell on me…

Ok I’ve had sex with a guy unprotected before, and could like smell his dick on my down there for like a week. He didn’t have bad hygiene or anything. And I’ve had friends tell me they’ve experienced that too. But now I’m smelling a guy I didn’t have sex with on me… like we fooled around a little, I blew him, he didn’t really touch me cause I was on the heaviest day of my period. But now like a week later, I keep smelling the scent of his dick. And it’s always when I’m like on the toilet, so I can smell my undies. I’m so confused. Is it just a ghost smell? Or is there an actual explanation?