I have already had my period but now i have cramps and im bleeding again?

Bleeding post period: If your period was "on time" and bleeding/cramps occur again shortly after bleeding stops, if pregnancy is possible, get a serum HCG test asap, as a pregnancy outside the uterus is possible, which needs immediate attention from a physician. There are other causes if the test is negative, so see your gyn provider for an exam and testing.