Have you checked her crop first thing in the morning? That's the only accurate way to identify a crop disorder. It's important to nail this down. Please refresh your mind about crop disorders so we'll be on the same page.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
Right now we have a bunch of dangling symptoms we can't really nail to any one cause. She has symptoms of starvation and weakness, symptoms of a static crop that may be overflowing into her larynx, symptoms of possible avian virus such as leucosis, symptoms of a possible respiratory disease, symptoms of a general bacterial infection. See what I mean?
We need to start at the top and rule things out so we just have a few to choose from. Otherwise, we'll be chasing treatments and not really focusing on a problem that could be killing her.
First of all, let's rule out starvation caused weakness. Give her a cup of warm water with a teaspoon of sugar mixed in. If you have any poultry vitamins such as Nutri-drench or Poultry Cell or Rooster booster, dump some in this cup of sugar water and give it to her. If she's too weak to drink on her own, you need to syringe it into her. Get at least a fourth of a cup into her right now. If you syringe, this is the safe way to do it.
Avoid the airway in the center of the throat just behind the tongue. If you insert the syringe into the esophagus as shown, no fluid will get into the airway. This will tell us her problem not being able to stand is weakness from starvation if she gains strength from the sugar water.
That in turn will point us to a crop disorder as the cause of starvation.
If she fails to revive after the sugar water after giving her a couple hours for it to work, then she may have a much more serious underlying condition such as an avian virus with its accompanying tumors on organs or a respiratory infection.
Thank you for your help.
