How old is he?
Is he able to urinate?
What and when did he eat lastt?
Any vomiting or lose or hard stools?
How long have you, seen salt and pepper in the box?
A cats appetite is the best barometer of his health so if he is eating fine he may have hurt himself.
Feel allover his back and tummy for any abnormalities.
If he continues to act like his tummy hurts feel for a hard object in his abdomen. That could be a full bladder.
The new kitty may have brought in fleas hence the salt and pepper in the box.
Just keep an eye on both of them for any developing symptoms.
I hope they will be fine.
Have a merry Christmas and a healthy happy new year.
If he is acting like that something is hurting him.
Could he have swallowed a sharp item?
Is his tummy swollen?
Has he passed stool?
Are you, sure he caan urinate?
He may have picked up parasites from the new cat.
He could have an infection or pancreatitis or even an injury.
If he continues to act in pain you will have to take him to a vet.
Please let me know how he is.I hope he will be allright.
Its almost impossible to diagnose him without seeing him All I can do is ask you questions and tell you what is might be.
A cats thats sick wont eaat but hes eating.
You say he is urinating and passing stool.
So that leaves pain and a possible injury.
Thats why he needs a hands on exam.
Let me know if you have more questions.I just want him to be all right.