So sorry, JammyJammy. Just terrible when one of your little ones die.
Sigh. This case also demonstrates how difficult it is to diagnose chicken disorders. I think we went through many possible things: something stuck in her throat, respiratory infection, kidney poisoning, sour/impacted crop. It's very hard to figure out what's ailing a chicken at least if you're like me, with not a ton of experience. I have The Chicken Health Handbook and it helps a TON with diagnosing issues. It's not fool proof, but this book really helps so much. One thing it does do is help me eliminate some things early on so I can get down to treating the fewer remaining possibilities.
Good luck, JammyJammy, again, my sorrow goes out to you. I can tell you really tried so hard to figure out what was wrong with her and help her. Hopefully, this experience will somehow help you in the future in some way.
Guppy

Good luck, JammyJammy, again, my sorrow goes out to you. I can tell you really tried so hard to figure out what was wrong with her and help her. Hopefully, this experience will somehow help you in the future in some way.
Guppy