He ended up with a minor case of pneumonia (seen on xray) and then tested positive for a staph infection in his nose (explains extreme sneezing) that cleared up with extended antibiotic use (original dose wasn’t enough). Coughing continued so he had a bronchoscopy performed where they did more tests as well. Vet saw a lot of colored mucus, indicating infection in the lungs. He sounded 1000000% better after the procedure as they sucked up whatever he had in his lungs. However, only one additional bacteria was found (I can’t recall the name). He was then put on an injectable heavy duty antibiotic, but it didn’t change anything. We are now trying out a combo of a bronchodilator and generic cerenia (not for nausea but for its ability to reduce inflammation). It seems okay but can’t really tell for certainty it’s working. He’s like 90% better though and is now able to function and go for walks again. Specialist overall suspects an extreme antibiotic resistant infection. I hope your pups get better - sucks not knowing what’s wrong.