Duckling throwing up

[rtflanagan]

I'm not sure what is up now. I was watching the babies and one threw up. I noticed earlier today she was whistling when she was breathing. I added ACV to their water. Bath has been daily. But now she threw up. He crop is FULL of water and she sounds gurgly (not sure that's a word). I tried to help her get rid of some of the extra water and got some out. But only 1-2TBS maybe. She is definitely breathing harder than the other .
What is going on and what can I do?