I rescued four little kittens from the street and found them a home

These kittens were born by a feral cat. People who lived nearby asked for someone to take the kittens away from there since it was a dangerous place for them. They had a big dog that almost chewed one of the kittens up and there was a road with lots of traffic nearby. The kittens were tame since they were feeding them for about a week already. I did take the kittens to a vet. They had fleas, earmites, a mild diarrhea and intestinal parasites. They were tested negative for feline coronavirus and panleukopenia. I took them home and started treating them for their minor issues. A mild diarrhea is pretty standard for kittens who live on the street so I wasn’t worried about it. Unfortunately two days later it got worth and one of the kittens, Basya, started throwing up and refused to eat. I took them to the vet again were they were tested for feline coronavirus and panleukopenia one more time. This time the test for panleukopenia came back positive. Because panleukopenia is a virus, there is no specific cure, so