Cramps after sex? What can this indicate?

Hi guys, I’ve had sex 2 days in a row (fri and sat) and I have been experience slight cramps after sex and I don’t know what this could mean. Yesterday I felt cramps and a bit sick/nauseous. It’s now Sunday and I still feel slight twinging/cramps in my lower tummy. I’ve been STI checked recently so it’s not anything to do with that!

On google it says things like early preg, implantation and other things so I was wondering what your opinions where? I would really appreciate it!