Early period?

Hey guys, I have a question my cycle is normally 30 days or so and I take ovulation tests and it peaked 4 days ago and today I started bleeding abruptly and clotting a lot and my period is 10 days early?? Why could this be I have PMDD and skipped over that. I just had an ultrasound and am okay I’m so confused. This has never happened and have never been early in my life.