My chicken is having trouble walking

[Pigeon_chicken2016]

My chickens tail feathers are down and she is very skiddish, and when I walked hear her she tried to walk away but she would wabble and then use her wings to help her balance a little better "she normally runs and/or flys away" and we have horses too and she was hanging out in there, When I first noticed her she had dirt ob her back. In not sure if she got stepped on or not, mostly because like I said before she is skiddish. Please any help will do,
Thank you

 

[Eggcessive]

Sorry about your hen. How old is she? Does she still lay eggs that have normal hard shells? Is she limping at all or is she waddling mostly? While she could have a back injury that is causing her problems, she might have a resporoductive disorder, which can cause duck walking and tail down. Have you checked her for a stuck egg by inserting a clean finger inside her vent? Was she vaccinated for Mareks disease? If you could take a short video of her walking, and post it to YouTube with a link posted here, that would be good.

 

[Pigeon_chicken2016]

She was vaccsinated and she is about 3
years old but ever sence the other day she has gotton worse and now cant even move without flopping around, and I hope that I can help her. And she has been vaccinated,