I'm sorry you're going thru this. We are too with our 14 wk Buddy. The 1st vet said it would resolve on its own. A few days later I went for a 2nd opinion. After 4 days & a lot of panicking
we started to see improvement on Zithromax. I think kennel cough incubates for 5-10 days(?), so it likely was picked up at the breeders or maybe the breeders vet if the dog had a recent appt. From what little I understand, LOL, this is very easily passed from one dog to another & sometimes from us - sort of like we're the doorknob the dog just sneezed on & the next dog we touch gets exposed from us. She mentioned seeing more resistant strains & more bacterial infections which is why she went straight to Zithro and not to stiffle the cough too much or it might settle into pneumonia. Anyway, Buddy is improving but still not eating too well and coughs after drinking or coming in from the cold. I do hope things improve soon and your other dogs aren't affected the same way. I heard putting him in the bathroom when you take a shower also helps but we didn't need to do that with Buddy, just kept him warm and quiet.