What does it mean if you had sex in the morning and got your period at night it only lasted two days and you're still cramping?

Could be normal: Sometimes orgasm can cause uterine cramps that can last for quite a while. Also, semen has prostaglandins that can make you cramp if you didn't use a condom. Sometimes the cramping can make you bleed which then makes you cramp more which then makes you bleed, etc., etc. . Rarely, bleeding and cramping can be a sign of infection. Watch for fevers. Get an exam if you aren't getting better.