Pain? Period pain or something else!?

I had sex on ovulation day, a week later I had an one extreme cramp.. which was worse than my average period pains, it lasted a few minutes. I had to come home and leave my dad at the shops, it knocked me sick🤭 I wasn’t due for a week (due not tomorrow but the next day) and since haven’t had one pain? What could this be? I’ve had thin milky cervical mucus. That’s about it, my last period was only 2 days long.

Never had this before! I don’t have a clue what to think😱

I’ve also been so thirsty😩