I have a flock of 10 birds, just a few days past 12 weeks of age. My largest bird...the strongest, fastest grower aka "Big Bird" was very droopy and weak in the legs a few days ago. I moved her into quarantine and watched for abnormal poop. She was pooping dark green poop for over a day. Finally figured out it was because she was not eating enough and just dumping bile. She would also have clear watery poops. She was drinking well, and started eating well when I gave her her own small chick starter type multi-holed feeder. Her head was drawn back into her body so I know she didn't feel well. But her feathers weren't fluffed like a really sick bird. I've already dealt with coccidiosis and know what the bird looks like and what the poop looks like. She also seemed cooler than normal even though our nighttime lows are only in the 50's and she's fully feathered. But I reasoned that was because she was not consuming enough food to have normal metabolism that would make a normal body temp. Does that make sense? She seemed to improve some over the first night and so I let her out for some free range thinking she might need to eat some grass to improve digestion. She stayed in isolation room again that night. She ate a little grass but tired easily. She did eat from the automatic feeders we made most of the time the other birds were out ranging. (They are buckets with the curved holes in the sides) When they all came in I began to realize it had been a while since I had lifted the height of the feeders. Which seemed to help everyone. No one had to tiptoe to get to the food so it wasn't too high for them. I thought maybe I had found the problem! She was the tallest and maybe she was refusing to eat because it was too low! Last night I isolated her in a rabbit cage and put food and water in with her. Her poops were normal this morning so YAY! I thought she was okay. She was eager to rejoin the other birds and so I let her in with them again today. But I was gone all day and couldn't monitor her. I felt her crop and it was still pretty mushy. Not tight like the other birds normally are at the end of the day. When I let the other birds out to free range and her into the isolation room, she started making a sound almost like the honking of a duck! She panicked when all the other birds and I left the coop. I let her out so she could free range but she just came to me and was happy to sit in my lap to watch the other birds and still kept trying to sleep. So her energy level is not up yet. So I have ruled out: coccidiosis or other major problem disease neck problems or other issues with the feeder size/height crop impaction and/or sour crop. I smelled of her mouth and didn't detect anything unusual. Oh and they are on Elite Texas Natural chick starter feed. Will be switching them to grower with the next bag. I don't use antibiotics, only natural means of health like Apple Cider Vinegar, garlic, natural coop cleaning, deep litter method, essential oils in water, etc. And the Elite food has probiotics added already so that is covered. What am I missing? Thanks in advance to you veteran chicken farmers!