Oh dear. Like my mom's cat, I wonder if there is inflammation in his intestine? I don't KNOW that Shiney has that, but it seems possible since the painkiller is helping him so much.
If it comes to it, I am hoping the vet and my mom will try some prednisone just to see if it helps without the x-ray testing and all.
HUGS and many many prayers for Fister.
"You can say any foolish thing to a dog, and the dog will give you a look that says, 'Wow, you're right! I never would've thought of that!'" -- Dave Barry