Urban,
I had something sort of similiar. It turned out to be botulism and the hen did get better. I am so sorry you are having this problem right away. Try to learn everything you can from this and share it with us. I sincerely doubt you are responsible with your hen house roosts. Chickens are clumsy for the most part and can handle a lot of bouncing around, falling off of things.If your chicken is willingly eating add some good yogurt (like the greek with tons of probiotics in it) and some electrolytes (a teaspoon or so), to the food. Apple cidar vinegar in the water is good but you have to get it from a health food store (with the Mother in it). Lots of people put electrolytes in the water but I am against that. You want the chicken to drink and flush out the system.
Try not to worry too much.