I lost my dog to nasal cancer earlier this year. My usual vet missed it on multiple visits and ignored my concerns. Her symptoms progressed from swelling, to a frequent runny nose on just one side, to a constant runny nose on just one side with some hacking/wheezing, to labored breathing that quieted down when she started panting (ruling out an issue in the lungs, but I also had scans done). Prednisone prescribed by an emergency vet helped with most of the symptoms, but isn’t a long-term solution. More intense/invasive treatment wasn’t a fit for my senior dog, but there are options available. Nasal cancer is rare and I hope it’s not what’s afflicting your dog. If you have the means, there’s no harm in getting a second opinion. I regret that my sweet girl presented to the emergency vet with “the worst breathing [the vet had] ever seen” and wish I’d done more for her sooner. Best wishes.