I have a Rhode Island Red that's probably about 3 years old and is having trouble walking. She seems still somewhat perky, if you will. She's not blah or droopy or anything. She just can't walk very far. She's not laid eggs in a long time so she's not egg bound. She stays in the coop and just laying there. However, if I go in to see her, she gets up and hobbles away. I've been giving her some Vitamin B the last couple days. Does anybody have an idea as to what this may be?