Ann, did the vet ever try to pinpoint anything like a fungus or ask about the possibility of them getting into something toxic?
Nasal cancer is usually pretty slow to develop...certainly not just over a matter of days or a couple of weeks...so I doubt that that's what happened to your two furbabies.
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."