Peppermint or peppermint tea can help with nausea. If giving tea, he may or may not take to it; if not, you can tip his head back, give the tea into the corner of the mouth, slowly, using a syringe, and he will swallow it. You can give oral electrolytes such as Pedialyte the same way to help with hydration. Nutri-cal is a good way to combat hypoglycemia and stimulate the appetite as well. However, as far as I know sub-Q fluids do not actually cause hypoglycemia, but it would be fighting the illness that takes a lot of energy, and the inability to digest his food properly to absorb the calories. Your vet can help you out with the right amounts for your puppy's size and condition.
a/d is a veterinary prescription diet from Hills. Your vet will carry a/d or a similar convalescence formula. They are wet canned foods, which could help with hydration, and have a very fine/pasty texture to make digestion easier. You might want to talk to your vet about which one is best, as you can get what you need from another clinic, too. One advantage of a/d over some of the others is it is very bland and that might be better in the case of nausea.