Brownie has had a messy bottom for a couple weeks now and I thought was just a bout with diarrhea....but now, yesterday and today, has become slow, lethargic and won't eat. Is there an general purpose antibiotic I can give her? I tried giving her yogurt and cottage cheese, but she won't eat. I don't want my other hens to get sick too and we just introduced 13 tiny chicks into the roost this week too. What can I do? She's 2 and has always been very healthy. Thanks so much for any suggestions you might have.