The milk is probably making him constipated. If his poop is coming out in hard balls. Give him 2% milk or put water in the whole milk.

ya may be try 75% milk 25% water at first.. if he doesn't get better increase the water.. but let the doctor know about it...

banana has fiber in it.. so it helps to loosen up the stools...

@momtosid, he's not constipated just having trouble cause they're big balls he's pooping. Do I just put half milk half water??

try giving him 2% or more diluted whole milk.. I also heard banana helps with constipation...