I have a Black Rock chicken, approx 2 years old. She has been poorly for a few weeks now. Took her to the vets, who thought she had some infections and prescribed anti-biotics. We also wormed her at the same time. She seem to pick up, but this only lasted for two weeks. She is now unwell again. She has a droopy tail, is very lethargic, but is still eating. Her poo is extremely runny and white in colour. Not sure is she is drinking. Any ideas what could be wrong.