I was hoping to have some responses to my request for additional information. A dog's breath often smells metallic due to blood. The most common cause is dental problems and you can usually spot these as you can see tartar on the teeth and possibly red gums and darkened teeth. Kidney problems or diabetes can also cause bad breath as can a stomach upset or your dog licking his anal glands which are seeping due to being overfull, though you usually can smell this cause at both ends of your dog. First check your dog’s mouth, if it looks like it is his teeth, your vet can take care of this problem. I’d try adding some regular unflavored yogurt (not fat-free) to your dog's food for a week or so and see if that doesn't help solve the problem
As for his coat, if it is a musty type smell, he could be starting with a yeast dermatitis. This occurs when a dog has injured the skin usually the result of scratching which can be caused by fleas or allergies to name a few.
Yeast likes areas such as between toes, armpits and ears. Selsun Blue Shampoo can help with Yeast dermatitis. When shampooing, lather and leave on 15 minutes before rinsing. These shampoos are not meant to be a cure, just a relief until your pet can see a Vet. Benadryl can be given to your dog, the dose is up to 2mg per pound every 8 hours for itching due to allergies.
You can read about allergies here: http://www.vcahospitals.com/main/pet-health-information/article/animal-health/allergy-general-in-dogs/428
Here is a site that goes over itching in dogs.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer.