I'm sorry we almost lost a puppy due to the same reason but we were able to save him with a technique I learned from a vet. (Hold it like a taco in your hands supporting the head with your fingers and then taking it and swing it up and down) it's supposed to force the fluid out its nose and unblock the airway.

Aw that sucks I remember my dad going through it when I was a kid and our cat had kittens. It's hard 💖