Hello again, and thanks for your reply.
It's possible that your puppy's system is not processing the food he's eating, properly. If the Iams you're feeding contains corn, soy, wheat, dairy products and artificial preservatives or colors/flavors, these are common allergens for dogs. Some well recommended brands which contain no allergens are Wellness, Canidae, Innova, Natural Balance, Halo and Newman's Own. There are many more available in your major pet supply store. Of course, make sure you're only feeding puppy food, and he's not getting into any non-food items. Puppies LOVE to take everything into their mouths, like human babies.
He could have a dental or gum problem, or is teething. This could cause a funky smell to his breath and if there is any bleeding in his mouth, the metallic smell could be blood, as the iron in the blood makes it smell metallic. There could be a chemical imbalance in his body which is causing the smell, as well.
There could be hidden blood in his urine, if it has the same metallic smell, or again, it could be the way his body is metabolizing what he's eating.
I'm glad to hear that all his functions are normal and he's active, but it would be a good idea to have him evaluated in person by the vet, and have some bloodwork and urinalysis run, to check for any abnormalities causing this smell. Also, have his anal glands checked for impaction, as this may be the cause of the smell, but he would most likely be 'scooting' (rubbing his butt on the floor) and/or licking there, excessively, if his anal glands were bothering him.
This breed is also more prone to develop Von Willebrand's Disease, which is a blood disorder, so he should be tested for this at the vet's, as well.
I hope all will be well with your puppy!