I have 14 month old leghorn who is very ill. She can't walk properly and is very unbalanced. She just sits on her side in one spot all day and eats very little. She keeps on shaking her left leg. Her poo is normal.
check to see if she is egg bound. you can see the vent "wink" and sometimes the egg will be visible. if this is the case give her calcium and a warm bath.
she may just be injured, they will usually get better on their own if you can keep them eating and drinking. sometimes adding a little sugar to canned creamed corn will get them eating. sometimes adding sugar to water will get them drinking.
i hope im right too. if you have other birds, make sure she is separated from them (just in case).
i don't know if this is a good practice, ive heard of people rubbing absorbtine (horse liniment) on wounded legs.
i have also heard of people giving baby asprin, and im pretty sure this is safe as long as you don't do it a lot.