It sounds like you need some professional advice to make sure your puppy has not got an internal infection. A local pet shop might be able to steer you in the right direction, although if the condition persists a Vet should be consulted.
My puppy won't eat, finally got him to drink a little and has been sleeping all day. His tummy felt hot. I've been keeping him cool. Yesterday lots of play time and heat also drank some pool water. Is he going to be ok?