Hi, I would definitely take him to the vet ASAP. Anytime you get a new puppy your vet should check them out to make sure the little one is healthy. Blood in the stool could mean many things but a vet could make sure that it is not life threating. I would also buy a tube of Nutrical which is full of wonder things for a new puppy and especially if they don't want to eat.
Good Luck!
Living Dust Mop Gang
