I am three weeks away from my period, i am on the pill, and when i went to go to the bathroom a big amount of bloody tissue came out. i had bad cramps?

Irregular bleeding: This would be considered irregular bleeding and is not really that uncommon, even if you're on the pill. It's likely tissue/blood retained from your last period that just decided to come out today and your uterus is contracting to get it out-thus the cramping.Take some ibuprofen, naproxen, or acetaminophen to help and use a heating pad. Keep taking your pills like normal. Should have normal period