weird period

Maddie • Sun, Jun 11

So I started birth control like 5 months ago and my period always comes on the 3rd or 4th day of the sugar pills, it then lasts for 4days. The 3rd day day is almost no blood and the 4th is none. But I woke up today on the 5th day with a completely saturated tampon with a lot of thick clots. Any ideas?