If I am understanding your post correctly, your puppy is 25 days old? Or have you had him for 25 days? If he is 25 days old, that is very young to be away from the mom. Generally pups go to new homes after 8 or 9 weeks. A super young pup will sleep alot. If you are concerned though, a trip to the vet might be a good idea to rule out health issues.