Heavier period? *TMI*

So I’m almost 30 years old and obviously had my period a long time. I’ve used the same pads for years and my periods are generally on the medium flow level every month.

The 1st day is usually pretty light and hardly fills a pad. 2nd day is heavier than the first day, 3rd day a tad lighter than day 2, day 4 lightens up and turns to spotting and day 5 is light spotting. It has been this way for YEARS.

Suddenly this cycle has been a tad different. It’s day 2 and my period has been SUPER heavy to the point it filled up an entire pad(rarely happens that a whole pad is flooded) and it had some clots in it, not to mention I leaked out the back and went through my clothes.

I have been taking prenatal vitamins but would that cause my periods to get heavier suddenly?

Is that normal? What other reasons could make my period become that heavy?

I do not have painful periods, no PCOS, endo, etc.