If he's on Diamond Puppy...that's not good food.
"Chicken By-Product Meal, Whole Grain Ground Corn, Wheat Flour, Chicken Fat (Preserved with Mixed Tocopherols)..."
Diamond Naturals Puppy not as bad.
If he's on the regular Diamond Puppy then please change it right away. I would not bother with a gradual switch. If his stool is a little loose for a day or two that's not a big deal.
Orijen, Fromm, Acana...something grain free may be all he needs to settle those eyes down. Some bullies have issues with seasonal allergies early on but it's usually an issue with dogs that are a bit older. Could also be an early sign of entropion. Have him evaluated at his first Vet check.
Please post some more pics.