Red Pullet died

Hello all!

Yesterday I had one of my 3 red pullets die. I had noticed some differences in her from the beginning, but wasn't sure what to do.

From the moment we brought her home she NEVER stopped peeping..... loudly. Everyone else was happy and content, and she would just stand and yell.

At a day old she was a little on the small side. By 5 days she didn't look like she had grown at all.

She started to feather just like the others, but her feathers just looked ratty. Like they weren't full feathers. She also never really opened her eyes a lot. She would, but she would open to look around then then close them again. She even kept them closed while she peeped. I did not see any eating or drinking problems, and did not see any problems with her poop. I did have to clean her up once, but I had to clean others more than that for the first couple days. I'm concerned that I didn't do something to save her because I didn't know anything was really wrong, but by far my biggest concern is that she had something that she could pass on to the others. They look healthy so far, but of course now I'm paranoid. Every little thing is a possible start to the same problem. As soon as I found her I moved them to a different tote, and then sanitized the water and feed containers. Any ideas??? Thank you in advance!!