Sorry to hear about Oscar.
I hope you find out what is causing problem. : (

I wonder if he is eating something that doesn't agree with
his tummy like a plant or something?
Rocky did not do very well on Nutro.
That is why I tried Canidae.
Sheba did well on both foods, but the Canidae was
easier on Rocky's tummy.

(Not saying the Nutro is the cause for Oscar tummy problems)