Weak, wobbly 4 day old with air in crop?

[Spottiechicken]

***sadly Chickie did not make it** any restrospective advice welcome..**

Hey y’all! New chicken mom as of two weeks ago. I got two rounds of chicks. The first hatched the 12th and are bantams. The second round hatched the 19th. Everyone was doing fine yesterday at 2-3 in the afternoon. Since then I noticed my littlest girl who is 4 days old not coming out anymore. She’s a cookies and cream chicken (I like spots ) The heat pad was at 85 on the floor underneath and 90 touching it. It’s sloped so a perfect spot for all should be easy to find. everyone seemed really comfy in various locations yesterday and on the camera last night. I increased it today to 95 for the little one. Now everyone is mostly sleeping on top of it and seem toasty. Started her on yolk this morning and some homemade electrolyte/sugar water last night. No pasty butt yesterday. Had some this morning that I cleaned off. She’s come out a little more since the yolk a few hours ago but is stumbly mostly. She has what feels like an air bubble on her right chest. I think it’s her crop but also not sure? She makes this little crackle when she breathes most of the time now. Is this a crop or could it be a ruptured air sac? Is this something I can save? What do I do??? Help please!!
update- flipped her upside down and with a little manual pressure was indeed an air filled crop with a yolk water mix

 

[Tookie]

Welcome to BYC! So sorry your little chick didn't make it.
Hard to know what might've been wrong. She couldn't just been failure to thrive and was never meant to live, or she had a crop issue (could be part of failure to thrive), or lastly like you mentioned it could've been a ruptured air sac. But like I said, its hard to know. You did the best you could and gave her a good life, as short as it was.