My period has been going on for 8 days usually last 4 been stressing a lot lately could this be the cause? also having cramps in lower abdomen

Yes: Stress can definitely alter your periods and make them come early or late, be too heavy or light, or more painful. If things normalize in a month or 2, there is no need for worry. But if you do continue to have heavier more painful periods, discuss with your gyne getting an ultrasound to rule out fibroids or other problems. If you are sexually active, check a pregnancy test just to be sure.