Extreme pain after sex?

So this morning after sex with my husband (he's 9-9.5 inches) I had extreme pain around my pelvis wrapping around to my back and down to my anus. Like to the point it hurt to move. It lessoned and went away with a shower. About an hour and a half later I wiped and had bright red blood, so I figured I started my period. But several hours later I checked my tampon and there was barely anything on it. Maybe a small smudge of red.

Has anyone had this and ended up pregnant? Or is this really just my period being weird?