What Causes Weight Gain And Cramping Under Ribs After Having Unprotected Sex?

Okay I've lost my virginity to my boyfriend about a month ago and since then we've had sex about four times. One of those times, he went in really quick without a condom just to see how it feels and I'm kind of paranoid that I might be pregnant from pre cum? I feel like I've been gaining weight but it might just be from over eating, I've had cramps in the area right underneath my ribs and if I remember right I spotted a little blood but nothing major a couple weeks ago. I feel like I'm just paranoid though? Give me some advice?