I have a Rhode Island Red hen - about 3-4 years old that has recently started having balance problems. It looked like she had a limp at first, but now she can only stumble to the right. She trys to be active - keeping up with the rest of the flock. She eats/drinks well, but her comb looks dull and is leaning over and she just kind of stumbles and eventually falls on her right side. Any ideas?