welcome to healthcare magic,
minor bleeding from umbilicus
may be due to an infected boil,abdominal wall abcess,infected urachal cysts or endometriosis
if this phenomenon is concurrent with menstrual period.
any amount of bleeding from umbilicus should be evaluated.but don't be impatient,it is not a debilitating condition.get a doctor near by and have some investigations like examination of discharge from umbilicus,CT scan
of abdomen if your detailed physical examination supports it.