I would give the Nutrical if your pup is not eating much too stimulate appetite also after he/she has played. You wouldn't want blood sugar to drop.
I've known some who give it on a daily basis with pups that are the same age as yours until they have somewhat of a "set"eating routine or are a little older. If you've ever seen a diabetic have low blood sugar(woozy/wobbly/can't focus) these are some of the same symptoms that can happen if your pups sugar gets too low. You can put a tiny bit on your finger and let your pup lick it off or rub it on his/her gums.