Cramping after sex

HK • Sun, Nov 29 • Married to my best friend. Alexis is 7, Oliver is 2 and Mackenzie was born 6/1/16

So I had sex yesterday and have been cramping ever since. It's been about 24 hrs and it's really freaking me out. I keep checking for blood but none, thankfully. Anyone else gone through this? This never happened with my other two. TIA.