I'm having a somewhat similar problem. I filled the bathtub for my two week old ducklings to swim in (this would their fourth time swimming). They were all fine when I first sat them down on the brick, but within minutes, one began drooling and making a awful gargling sound. I picked it up, and it's neck appeared swollen. Without thinking, I massaged the neck (gently) and a bunch of water came out of the baby's mouth, as well as some very water soaked food. It started cheeping again, then the rest started doing it, and I repeated the process. They are all fine and cheeping in the brooder now after I dried them off. The lumps appear to have gone down. Did they engorge themselves with food and drink too much too fast? Will they be okay? What should I watch for? Did I do the right thing or did I react stupidly?