Sorry to hear that Nicky is having this problem!
I don't have any personal experience with it, but I've known of dogs prone to collapsed tracheas that have passed out that way. Glad you're taking him to the vet! When is his appointment?
"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."