A bit frustrated..

[Wyorp Rock]

I would say any bird can have Subcutaneous Emphysema. It can happen from an injury/wound or infection from respiratory illness.
A lot of times the bird will re-absorb the air and the air sac can heal on it's own. Sometimes the air can be released by a sterile needle and antibiotics administered.

A chick that is dropped or picked on due to overcrowding could be susceptible to this condition. It's hard to see in the photo, but it looks like she had quite a few feather plucked at? I see some redness there.

 

[Dkbahoo]

I couldn’t tell if the feathers were plucked or if the skin was just that expanded.
It’s usually more obvious when feathers are plucked at least in adult birds because I’ve rescued a fair amount of chickens and have watched their feathers grow back, but I don’t know if chicks are different and there wouldn’t be an evidence of where feathers once were.
It was pretty sudden too. Like I feel like it has happened overnight every time. I tend to my chicks and chickens constantly.

 

[rebrascora]

Can we rule out pasty butt as the cause of the bloat?? It is difficult to know a persons level of experience from reading just a couple of posts, so apologies if that suggestion seems insultingly basic but it is the first thing I would check for in a chick with a swollen belly.

 

[Dkbahoo]

And it seems like they all get along, but the barred rocks are a bit more skittish than the others and are still inside. I literally just bought another coop and was planning to move them outside with more space, but then this happened and I wasn’t sure what I was going to do.

 

[Dkbahoo]

Oh yes. Definitely didn’t have a pasty butt. At almost 8 weeks they don’t tend to deal with issues like that. I’ve only ever had issues with that from hatchery chicks that traveled a few days.