Nothing else going on at all. I mean, they occasionally sneeze but I looked that up and apparently if the food is really dusty (which it is, they actually bathe in it), that can be the problem. And it is only like once or twice a day among 15 chicks.
I am starting to think that she may have just been picked on by the others to the point where she got no sleep and that drove her to eat less. I just gave her some egg yolk, so I am going to see how she is doing in the morning, since she is isolated now and will be able to rest.
I have no idea what else it could be- if you have suggestions please feel free to post them here.