what's wrong with my chicken?

[Hardy Hen]

i have a sick chicken and i don't know what's wrong with her. she hasn't lost weight and she's eating and drinking fine. her comb is a nice, deep red and her noes isn't runny and her eyes aren't watery. she is having a really hard time balancing herself. today i noticed that she was tipping forward when she was pecking at the ground. she would also look as though she was slipping on the ground and she would start to lean to one side. she is a little inactive and today she was lying on the ground trying to soak up as much sun as possible. when she trys to jump up onto something she falls backwards. i put her on medicine for a week because her behavior was similar to the way some of my chickens were acting when they got the flu. i took her off because someone here told me they shouldn't be on medicine for something i'm not sure they have. her poops are pure liquid. the other chickens aren't ignoring her and i will not separte her from them because i know that would cause her a lot of stress. i'll call my local farming store tomorrow because they usually know what's going on with farm animals. but please if anyone has any idea please help. please...

 

[countryboy]

what color was the runny poop? and if it has been going on for awhile I would think she is getting dehydrated even though she is drinking water. I would think some electrolytes might need to be added to the water to combat this tho I am no expert. only other thought that came to mind was cocci but I don't know.