They're on "clean shavings" - that's what the folks at the feed store called them.
So, it's possible that it's crop-related, but I don't feel anything "hard" that I could sort of massage down, you know? However, I noticed tonight, when I gave them water, that they just drank and drank and...
I don't think it's the crop - it's on the side, right "above" the wing, but it's also very soft - like there's just air in it. Baby chick (3.5 weeks now) doesn't seem bothered by it. I did a bit of searching and saw that it often goes away, so I'm hoping it does the same for this little...
So, one of the two chicks that just went through four days of being close to dying, has what feels like an air bubble on its neck, close to the wing. It was noticeable before, but I was more concerned about their more serious condition, and it wasn't as big earlier. I noticed tonight, though...