What Causes Black/dark Brown With Clots Periods With Bloated Stomach?

when i get my period it only lasts 3 maybe 4 days and its black/dark brown with clots the whole time. I have a history of PCOS. I am not pregnant. what could this be? I am33 years old, 5ft 4 and between 11 and 12 stone, maybe closer to 12. I also want to eat lots when I have my period even tho my stomach feels bloated/full, thats the only time I get like that. I get thrush like sypmtoms almost each time I have my period lately too.