Cramping after Sex?

I'm 33+3 weeks pregnant and the last couple of days, I've been having light cramps like I used to get the day before my period was due. I think it was dehydration since I was busy/stressed those 2 days and forgot to drink that much water, however today I didn't have any cramps since I've been consciously been drinking a lot more water.

However after having sex about an hour ago, I've been having cramps both in my belly and back and it's more like period pain, like not intense pain but a bit stronger than what I've been feeling the last couple of days. I'm not too concerned because it's a constant 'pain' and doesn't come and go like contractions.

Is this normal? Has anyone else been feeling the same?