Lethargic hen, not eating or moving, advice please?

[SeptemberQuail]

Hello!
My hen, Cookie has fallen ill- I believe its only started yesterday as during the beginning of the week she seemed normal and was eating properly.
Yesterday I found her just standing inside the coop, refusing to move, and ate very little. I convinced her to eat some scrambled eggs and some soggy chicken feed (she normally likes eating the pellets when they're damp) but she didn't seem too interested.

This evening after school when I came to check up on her, she had resorted to standing completely still, puffed up and swaying slightly. When I pick her up and gently put her back down, she seems weak on her legs. Mum's told me that she's been staying in the same spot pretty much all day. Also very subtly over these past few months, her comb has appeared to have shrunken.

I have no idea how old she is, but she has long retired from egg-laying.
She's also an ISA brown.

I've tried coaxing her into drinking some electrolytes which wasn't very successful, but she did drink a very little amount.

I'm just looking out for any advice on what I can do to comfort and treat her, what I should look out for, and any suggestions as to what could have caused this sudden drop in health.

Thank you very much in advance!

 

[Eggcessive]

She possibly could be suffering from one of the several reproductive disorders that plague older chickens, such as internal laying, egg yolk peritonitis, salpingitis, cancer, or others. She looks like she is stiff, and has a wide stance, which can be common in those. Here is some reading about those things, just in case that is what you are seeing:
http://www.chickenvet.co.uk/health-and-common-diseases/egg-laying-issues/index.aspx
http://scoopfromthecoop.nutrenaworld.com/tag/laying-issues/

 

[SeptemberQuail]

Thank you for your response! The articles were definitely helpful.

As of this morning she is clearly not fairing any better than yesterday as she can barely stand. She's resorted to lying down now. When I pick her up her feet are curled up. And her head sways slightly as if she is suffering vertigo.

I've read what the articles said but I'm wondering if there is anything else I can do for her?