I had a normal period it lasted a little longer than it normally does then a week later i'm having another period. what could thus be?

Ovulation bleeding: Bleeding a week after a prolonged menstrual period stopped is consistent with ovulation bleeding. Estradiol concentrations measured in serum around the time of ovulation drop and in some women or during some cycles drop to an extent that it can cause hormone withdrawal bleeding. Usually this kind of bleeding stops after a day or two.