Irregular period/Bleeding

I usually get AF on my due date & bleed for around 4 days. I get sore nipples and cramps for the first day or two.

This cycle, I spotted/bled lightly on and off for about 5 days and then a day or so later AF arrived 4 days early.

It was very light compared to usual.

Come day 4, I started to bleed heavily.

Today is now day 6 and I am still bleeding heavily. Still experiencing some strange cramps all day every days and nipples are still extremely sore.

This has never happened to me before and I am so confused as to what it could be!

Any thoughts?