sick chick, should I put her down?

[Old Macdonald]

I have a blacked barred that started breathing funny right after I got her. She's 4 weeks old, lives in a large crate with 5 other chicks, lined with pine shavings, gets fed medicated crumbles, has access to grit. the temp stays right around 80 degrees. She seemed to be developing normal, has feathered out and gotten pretty big. she always breathed funny and over the last 24 hours has seemed to fade fast. she can't stand, won't get up and move about, stopped eating and drinking. I have taken to holding her, which she no longer resists, and dipping her beak in a tray of milk. she will drink a little but that's it. trying to keep her hydrated and give her a little strength. I assume it isn't bacterial or viral because all the other chicks are in perfect health. So my question is this: Do I put her down? I have no idea if she will recover but she seems to be getting worse. It breaks my heart to watch little Hazel suffering.

 

[dawg53]

She might have pasty butt, it might be too late if she does. I Recommend that you cull her.

 

[Old Macdonald]

She had pasty but pretty bad when I first got her but I took good care to clean her regularly. She hasn't had any pasty butt for the last 2 weeks. don't think that's the issue but I'm a true novice so I don 't know.