im comfused please explain this!!!! period or miscarriage?

S

i usually bleed for 5 days and its very heavy for the first 3 days and my period is regular like clockwork. but this month it came 4 days late (17 days dpo) and started with cramps and spotting and got heavier and today is the 3rd day with barely any flow but im passing a lot of clots. i had sex 5 days before my fertile window. could it be that i got pregnant and miscarried? additional information- I've been taking isotretinoin for acne