Jynelle--
Is Oscar puking soon after he eats??
It may be the food. Kito is very picky, and a pain sometimes about eating, but there is one kind of food he absolutely cannot eat--he pukes it up every time.
It's probably worth a shot for you or your mom to pick up a bag of something different next time you're out, and start there.

Nutro is a good food, but it's not for everyone--maybe Oscar's little tummy can't handle it anymore.