If a puppy or dog is eating only kibble, then expect dry skin. Dogs need Omega fatty acids. You can buy these in gel form at a vitamin store. Look at the adult does, then you can figure out how to break it down to his size.
Fish is also good. Sardines and salmon (in a puch, not canned)
You also should not use baby shampoo. There is an ingredient that can be harmful to pets. Instead, you could use Dr. Bronners pure castile liquid baby mild liquid soap. You can dilute it way down. Remember, you don't need tons of suds to get clean.
Dr. Bronner's Magic Soaps Retail Store: Baby Mild Liquid Soap
Then always use a conditioner afterwards.