I always have some value fish fingers in the freezer, the very cheap shop's own ones, at ASDA I think they are about 25p for ten, I cook them and then mix them in with Instant Mash made up with just water, again just value instant mash.
Feed that till the runny poohs stop and then gradually introduce normal food. A friend of mine used to work for Springer Spaniel Rescue, and it is what they used when they got a sick or starved dog into rescue, you can have them in handy for whenever you need them.
Chicken and Rice is also another food that is light for an upset tummy.
Hope everything clears up, but if you are at all worried or see any blood, or the puppy starts to be unwell get him to the vet immediately.
My daughter once ate the cheap fish fingers by mistake and she said they tasted fine, but I am a Birds Eye girl myself, the dogs seem to like the cheap ones though, they do smell quite fishy !!!
