As a second time mum... it started like period cramping, every 10 or so minutes.... then getting stronger as they got closer. Now you can have these types of pains for a while, they stop and keep going for weeks possibly. It is why some people are 1 or 2 cm dilated for a week or 2 before they give birth. The pain tends to need to be in the area you would normally feel cramps for periods, and spread upwards the more you progress.
I hope it means that your cervix did some work and opened up! I couldn’t find any studies that would pinpoint what sort of pain level or type of contraction we want for cervix to start dilating, I just know some contractions will thin out the cervix and dilate it. So I really hope your pains here and there are the sign that it’s working as it should be :) I’ve had something similar (although no sex because just not in that mood haha) and I was told at my 37w appointment I was 1 cm dilated and 50% effaced so I really hope it means something similar on your end too