Why does my cat scream when using the litter box?

[beez]

I am not a vet, but would guess either constipation or a bladder infection. Give her a few oats and soy milk with her food for the constipation. If she continues screaming, get her to a vet.

[Random]

she might be in a lot of pain. She is probably neutered (female term)

[Jonathan]

I don't know but I really think you ought to call a vet.

[♥ Kyndell ♥]

Take her to a vet...it may give her pains