My hen will not eat, feels hot, and is breathing hard

[Eowyn]

Yesterday, I isolated one of my hens because she was sitting in the coop with ruffled feathers. Now that I can keep a closer eye on her, I've noticed that she isn't eating and if I stick my ear close to her mouth, she sounds like a dog panting. Her poop is mostly liquid with hardly anything solid in it (I'm guessing her poop looks like this because she's not eating). She feels hot, but I haven't taken her temp so I don't know for sure if she has a fever or not.
She's a Barred Rock chicken and is six months old. Is there anything I can do for her, or should I just put her out of her misery?

 

[AshPack]

Is she closing her eyes? does she have anything in her crop? is her feaces completly clear?

 

[Eowyn]

She's closing her eyes about halfway, her crop feels empty, and she has a little bit of white stuff in her poop. Also, she has been drinking a lot of water lately.

 

[kidcody]

So sorry to hear about your hen! Have you checked her to see if she is egg bound?

 

[Eowyn]

My hen just died, but thanks for your help.