I had a 4 month old chick down last week, thought he was going to die, but he's now perfectly fine. It took me a while, but all I can figure is that he was very very dehydrated. Once I got some fluids in him, he had very watery diarrhea, but as I hand fed him fluid from a dropper, he got stronger, started eating and drinking, and his poop firmed up. Now a lot of chickens in my flock are having diarrhea, though none of them are showing any lethargy or any other symptoms. One was coughing when I let them out early yesterday morning, but I haven't seen any coughing at all since then, and the one that was coughing is still acting fine, no more coughing. I do have one 10 week old chick who was sitting puffed up on the roost just now when I went out to give them new water, this time with electrolytes, but he's very bright eyed and chirped at me, might just be in for their daily noon nap. lol. Several of them have diarrhea, though. It's just watery, no blood, at least none I've seen. I have noticed the poop under their roosts in the morning has been much runnier the past month or so than it was in the past, but since it was just runny brown poo, not white or mucousy or bloody, I figured it was a variation of normal and didn't worry about it. Still not sure if it's relevant or not, but it's pretty gross. We did just enclose them into a smaller run. Before they were completely free-range, we are on 42 acres. We put up fences due to predator issues, including raccoons coming in for snacks in the middle of the day while we were outside! So now they are all together and pooping in a much smaller area than before, still plenty big! I have 40 chickens, lf and bantam, and their new run is about 15x20 (that's a small estimate, I think it's bigger, probably more like 20x30 or bigger. I am really bad estimating length, I think most women are) plus they have access to the much bigger pen our 2 goats are in. It has also been raining a LOT. Our well water gets kind of gross when it rains a lot, but none of the people are sick, so I don't think it's relevant. It just gets some sediment and an off odor, which I have been told is due to the rain washing organic compounds down, not anything to worry about healthwise. It stopped raining 2 days ago and the mud is starting to dry up. Could this be cocci? I have no experience with it, but i have been reading via Google. It sounds like the kind that comes on suddenly with bloody diarrhea tends to hit younger chicks and kills a lot of them. But there are other kinds that can cause milder symptoms. Is there any other explanation? Will putting some diatomaceous earth in their bedding help, do you think? Maybe also out in their yard, which is already now half dirt from the rain and mud.