I'm so sorry you lost your pup. It is always tragic to lose one so young. Just so you know, your pup did not pick it up at the vet. Parvo has a 10 day incubation period. He had already been exposed at the time he had his shots. It is possible that the vaccine challenge to the immune system did push him over the brink into showing symptoms, which may be why there seemed to be cause and effect, of vet visit, then sick puppy. Good luck with the other pup, he looks like he is a little older, so he will have a better immune system.