Does anyone have any ideas as to why my hen has weak legs? She's waddling around like a duck. Still seems to be eating fine, buy can't lean over to eat too comfortably. I read about Marek's disease, but she's an older hen and was vaccinated when she was a chick. I don't know what to do. I just lost a favorite hen to sour crop and I just don't know if I can handle another hen dying so close to the last death.