Am i pregnant if not can you tell me what you may think is wrong?

I had sex today, and i haven't had sex since the last wk of Feb. So, i've been off depo provera since last year and the last couple weeks i've been cramping and spotting. I know my periods coming back. So I think their is a strong possibility im not pergnant. But after sex today i was cramping but i had been doing that because my periods coming, but after taking a nap i woke up feeling bloated, and my stomach hurts when i ate last.The feeling comes and goes. My friend told me it happened to her before and it happens when you don't have sex in a long time. Do you have any answers?