3 days HEAVY period

I normally have 5 day periods that are 3 days of extremely heavy (soaking 4 overnight pads) and 2 days medium (i can wear a menstrual cup for 12 hours and then empty it and wear a pad to bed)

This cycle i had 3 days of heavy period where i soaked 5-6 overnight pads and still leaked out. There was chunks of tissue and blood clots the size of dimes (and a few a little bigger) which ive never had before. And then nothing anymore, rather suddenly.

I took a pregnancy test the day before my period was due and again after the heavy bleeding started to rule out miscarriage and it was negative both times.

What could possibly be going on here? Should i seek a doctor or just go about my buisness and keep on ttc.