Kitten screamed when pooping?

The vet just dewormed foster momma cat and kittens and the deworming meds made them have really bad gas.

Well I just heard one of my kittens screaming like hell so I went in there and the kitten was shaking and screaming and pooping. I checked the poop, it had no worms.

So I don’t know if it’s the diet I have mom on, pe the deworming med because they finished the deworming medicine days ago.

I keep mom on a diet of both wet and dry food because if she just eats wet food it gives her the runs. I cleaned up the kitten and it finished pooping and went back to playing but obviously the poop was super painful. It was runny poop

Any ideas?

Do you think this is remnant of the deworming meds or is it moms diet?