I started my period on the 2nd and it ended the 7th and now its the 21st and I've started again the cramps are extremely bad and the bleeding was heavier but now it got liter but the cramps are still strong

That. That is abnormal, so would be considered as dysfunctional uteirne bleeding. I don't know your age. If there is any chance you could have been pregnant and are having a miscarriage you need to be seen immediately. Sometimes stress or other issues can cause irregular periods. You may need to have your periods "re-cycled" with a hormone supplement to stop the bleeding. Please see a gynecologist for a complete evaluation. Also please be sure your pap smear is up to date.