Am I pregnant?

I had sex 3 days in a row (2 days after my period) about a week ago, and now I’m experiencing period like cramping and headaches followed by light nausea, I figure it’s just migraines because it was soon after my period that I don’t think I could be fertile that early and how it hasn’t really been that long since intercourse. But i don’t know why I would feel period like cramping if it’s just migraines.