What is going on?!

My periods are almost always very on-the-day predictable/accurate. The first two days are immediately heavy and then the next two are light and it’s over. I was supposed to start yesterday...which I *kind of* did but it was only a very very faint pink color when wiping after using the restroom and it’s been the same thing for 24 hours now. Nothing but that faint pink when wiping. Anyone else experienced this? I have no cramps, definitely 100% not pregnant, and it’s not even enough to wear a panty liner, let alone a tampon.