What Causes Headache And Pink Vaginal Spotting After Unprotected Intercourse?

I had unprotected sex 5 days ago. The third day I had a really bad headache the fourth day I bleed a little bit and it was light pink but it only lasted yesterday and not that much blood. And I had really really bad cramps. But today I'm fine! My period isn't for 9 more days! I need to know what this is.