I'm still quite new to chicken keeping, and this is the first one I've lost so I'm a bit rattled. I know chicks are susceptible to a range of things, and a lot of symptoms overlap which makes it so hard to know what it is unless you go to a vet... But I thought I'd try to get some opinions anyway. We got three Orp chicks at 4 weeks old, all still in a brooder together. The other two seem fine (for now *fingers crossed*). Yesterday I took them out to the backyard 'playpen' and while the two girls were exactly as usual he seemed a little uninterested. He did a little bit of scratching/pecking, walked around slowly a bit, ate and drank a bit, sat down with the girls, but not his usual full-of-beans self. It was evening though, and starting to get a little cool and a bit darker, so I actually didn't think much of it. This morning I checked on them and saw that the girls were running around like normal, but he was sitting on the floor. I picked him up and noticed he had diarrhea streaked down his fluffy butt feathers, looked a bit pale in the face/comb/wattle, and his legs were quite thin and veiny. I put him back down, he just sat where I put him. Didn't eat, didn't drink, kept getting droopy headed, eyes slowly closing then snapping open. He was breathing a normal rate, but with every exhale I could hear a bit of a wheeze or gurgle type sound. Nothing felt swollen, broken, out of place, etc. What I feel is weird is that he was sitting with his butt right up in the air, though his legs were flat as they would usually be. This got progressively worse over the next hour... His tail was so high up, he had his neck scrunched down weirdly and his head just slightly up. He wasn't chirping and wriggling at me holding and touching him, and he didn't try to jump out of his quarantine box (which is very unusual, this one was so feisty!). I turned to go wash my hands, grab my phone and take a photo to help with IDing his illness (because at this point, I didn't have great hopes for him), and I heard my partner yelling 'Oh no! He's dying!' from the room with him. I ran back in, he was violently spasm-ing in the quarantine box. It was over in a few seconds, with him dead, eyes closed, contorted and stretched out. After a few seconds, quite a lot of fluid came pouring out of his mouth and didn't stop for about 15 seconds. I guess this was the contents of his crop coming out? Just noting it as strange as he hadn't been eating or drinking, and even if he had or there had still been some left there from the day before, it was a light, watery milk looking fluid that doesn't match their chick starter. I'm quite sad, and I feel so bad that I couldn't protect him, or help him, or stop this... But what do you think it may have been? TL;DR: Diarrhoea, no blood Lethargic Weight loss and potentially dehydration Not eating or drinking Wheezing upon exhalation Paleness of the face Odd posture of wings and spine while sitting Slight wing shaking and seemingly weak legs Twisted/contorted neck and spine Spasms upon death Expulsion of fluid from mouth upon death I'm also somewhat at a loss as to what to do now, and I'm really worried about my other Orpies too, so any help would be greatly appreciated. Thanks in advance, Ticket. EDIT: My partner called the breeder and asked her opinion on what happened, and she said she'd never seen it before. Seems a bit unlikely to me, I'm sure breeders have seen lots of birds go, just as a sheer numbers game. But the weirdly bent neck/back and lifted tail thing seems so strange to me. Can anyone shed any light? Or is this all just standard chicken keeping stuff and I'm just still too green?