I'm 47 yrs old ii get my period every 21 days this month I had a light period for about a week. Then all of a sudden I'm flowing so heavy and clots are coming out. And have cramps so bad

Make an appointment with a GYN. It could be anything from just a wild fluctuation in hormones to fibroids to something serious. If you have been having sex, with protection or not, it could have been a miscarriage. No one can diagnose it online.