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I'm sorry about your hen.
How old is she?
Can you get a video of her? Upload video to YouTube and provide a link.
Bubbles in the eyes can often indicate respiratory disease like Mycoplasma. Common treatment for Symptoms is to use Tylosin, Tiamulin or Tetracyclines...
Poor girl!
She's struggling isn't she:(
Not sure what's happening with her. Her comb going dark, she's lacking oxygen.
Just in case, feel all over her body to make sure there's not something that feels like Air under the skin. Doubtful it's a rupture air sac, but I'd try to rule that out...
Can you get a video of her?
UPload video to YouTUBE and provide a link.
Any obstructions inside the beak, any lesions like canker or yellow/pasty material?
Crop emptying?
When was her last egg - any issues with laying or any fluid or bloat in the abdomen?
Nares (Nostrils) clear of debris?
Any...