Howdy
DebbieDoor
First up, I am definitely not an expert at what ails chickens and I hope that someone with more experience will chime in shortly.
However, they will probably need some more information to assist in hopefully diagnosing what ails your gal.
Who old is your gal? What breed please?
Has she reached laying age? Was she laying and still laying now?
When you say “her eating is different” in what way? What are you feeding her?
Is she pooping OK? How do her poops look? Below are a couple of charts which may help.
http://chat.allotment-garden.org/index.php?topic=17568.0
http://www.the-chicken-chick.com/2012/02/whats-scoop-on-chicken-poop-digestive.html
How does her eye look different? Some pictures would help but I am not sure if you would be able to post them yet; I believe there is a minimum number of posts before pictures can be added.
Has she been wormed?
Any signs of parasites, lice or mite?
How is her breathing? Does she sound rattly at all or appear to be having trouble breathing, open beak etc?
A drooping tail can be a sign of discomfort in a chicken and could be related to egg binding. If you can, gently feel around her vent area and see if you can feel an egg.