One of my almost 1 year old khaki campbell ducks just died. She was fine this morning and this afternoon. We have a spring fed pond that they swim on all day, and when I came outside tonight to put them in the coop I saw her laying in the water at the edge. I went and picked her up and she was totally limp. She didn't quack or squirm. I brought her in and put her in the tub with some epsom salt/charcoal/ drench water. She was twitchy, and her breathing was labored. She made a weird clicking sound when she tried to breathe. Then about an hour later she passed. Any idea what it was? I'm terrified for my other ducks now. I never want to go through this again. Thanks!