My baby cuddles is gone

Yesterday , my baby passed away in my arms. He survived from 10 a. m. yesterday and passed away at 2:20 p. m. Up until yesterday, he was eating and doing well. Yesterday morning, I realized something was off. He refused to eat and was hardly able to walk. I thought he was simply not responding when I called out for the puppies previous night. Yesterday morning proved different because he was barely walking. He made it so far just to see me come out my room after waking up. I was thinking that he became ill after eating something unhealthy. I covered him with a blanket and spoon-fed him water. I cleaned his mouth, etc. I was doing everything until the veterinarian opened today. I was providing all care for him trying to make him better. He was trying to drink water, and even walked around. When I picked him up again, things took a turn for the worst, and I knew it was over. In my arms, he passed away from what proved to be porvo. He was part of 4 puppies. I am still confused because he was perfectly fine and healthy. All puppies are getting vaccinated today