sounds like you might have a chocolate or blue-born puppy..or maybe some sort of combination.  It's hard to know without pictures..and honestly, with an unethical breeder it's almost impossible to know whether or not you're getting a purebred dog or a mix.  I would get him to a vet to get checked out and would recommend doing bloodwork before he's neutered to check for any underlying issues.     
				__________________  ~Magnifique Yorkies~  Purchasing from backyard breeders, pet shops, and puppymills perpetuates the suffering of other dogs. 
Educate yourself and buy from reputable breeders or rescue.      |