cramping and tight stomach 8 hours after

i had sex with my boyfriend last night before bed, we both got off and after my stomach started to get really tight but it usually does then passes. it has now been 8 hours since we’ve had sex and my stomach aches to the touch plus my lower back aches. i can’t even lay down without moving every two minutes. i’m 26 weeks pregnant and i’m sure it’s normal but i just want to make sure because i don’t want anything to go wrong