what's wrong with my chicken?

[Hardy Hen]

I have a sick chicken and I don't know what to do. She is a Buff Braham and she's 1 year old. I've noticed that she is having trouble balancing herself when she is climbing the steps to her nest and she can't fly up to the nests which are about 3 1/2 feet off the ground. She is also having trouble getting into the coop because she has to jump about 1/2 a foot to get in. Whenever she tries to jump or fly onto something she falls back. I have been noticing that she is eating less and not drinking a lot. Her poops aren't solid, they're pure liquid. She puffs up her feathers a lot now and doesn't seem as active. I haven't seperated her from the other chickens and they are not acting sick. The other chickens aren't avoiding her, but it's not like they're paying extra close attention to her. I noticed she was acting this way last Friday, Oct. 24. I put all of the chickens on Oxyteracycline Hydrochloride Soluble Powder (an antibiotic for specific diseases in poultry) on Oct. 25. PLEASE HELP!!!

 

[Guinea Goonie]

Please post the color and any other noticable traits the poop from your sick chicken has. ISOLATE YOUR BIRD !!! This may be cocci but you really need to get an accurate diagnosis. Medicting your birds blindly ( I do not think a small amount of tetracycline is uncalled for) can be a risky business. There are medications for cocci that are fairly safe, but you need an diagnosis. As I am learning, there are not a lot of medications recommended for chickens and people seem to experiment alot.