Most Helpful Guy
He's probably doing it because he regrets breaking it off and is thinking about you. I doubt he's doing it to get into your head.
Just block him if the notifs bother you, I wouldn't confront him. Let sleeping dogs lie and all.
Most Helpful Girl
Block him. Easy. But before you do that DM him ask him whats going on, see how he feels. Then after you figure out how he feels and what he thinks then you can decide what to do after that. Good luck!