I would also recommend that you contact the breeder to see what she was feeding him-you don't want to switch food brands abruptly because it can really upset their tummies, especially in puppies. Also, if they get upset tummies and get diarrhea, you need to watch them very closely to make sure that a young, small puppy doesn't get dehydrated and become weak or hypoglycemic.
With that said, if you're looking to feed him something different, check out the different brands at
www.dogfoodanalysis.com
You'll find that Science Diet isn't a very quality food, along with many others that vets like to recommend. Many vets will push brands like Science Diet, Eukanuba and others because they get money from those large companies toward their veteranarian practice, so please be aware of that.
A few of the popular brands that I see YT'ers feeding their dogs are Canidae, Royal Canin, and Chicken Soup. I personally feed my dogs a home prepared diet that includes raw and cooked meats, grains, vegetables, fruits, and dairy products along with supplements to ensure they are getting proper nutrition. I also sometimes give them a little Blue Buffalo brand kibble mixed with cottage cheese or yogurt for breakfast.
Before you choose any dog food or meal plan for your dog, I strongly urge you to do your own research online, and make the best decision for you and your dog based on your own findings.