Sick Hen-Help, please!!

[mvp chix]

I'm a newbie! New to chiken-keeping and new to BYC. I have 5 Black Copper Marans hens that are almost 20 weeks old, weighing maybe around 5 pounds. None have laid their first egg and have all been very healthy in both coop and free to roam the yard. Yesterday, my one hen, Dottie, started acting differently than the others. These are her symptoms: keeping one eye closed more than open; resting a lot more than the others and stretching out while laying down; eating and drinking just a tiny bit; losing quite a bit of fluff feathers wherever she laid, but not today; diarrhea-like stool.
I have done the following: inserted lubricated gloved finger in top hole in her bum to feel for broken eggshell-nothing; soaked her bottom in warm water; tried to cool her down keeping her inside garage for a little while. Tried feeding her scrambled eggs, but no interest. Today, I'm keeping her in the coop as I'm afraid my beagle will sense her being "down" and go after her.
Can anyone help me, please? I'm really very concerned about her. Thank you.

 

[DTRM30]

Here is a great site on what the normal range of chicken poop is for reference. Runny doesn't always equal a bad thing.

http://chat.allotment.org.uk/index.php?topic=17568.0

Not sure about the other symptoms. She is obviously not feeling her best though.
Maybe she is going through a tough molt - you mention she's losing feathers ....

 

[mvp chix]

Thank you for the tip on the poo. Yes, it looks like it is well within the "normal" range. Is she too young for a moult? And would it only last one day? It has been extremely hot here, heat advisories daily, however, the other 4 seem to be okay.