I have a 5 year old hen (rhode island red) who is not herself. First noticed a dirty back end, thought she had an egg stuck, but turns out not. She is slow mowing, tail is down, and her comb is laying over but not dis-colored. Gave her an antibiotic, nothing happened, tried a de-wormer and she is still the same. She still eats and drinks and is alert. Any other ideas what might be wrong or could it be just old age?