I agree with chickcrack that many times supportive care is pretty much all we can do with a sick chicken. After death, performing a necropsy to look at the internal organs will sometimes tell us what the problem might have been. When medicating with something that tastes bad, sometimes using a...
You may want to look up egg yolk peritonitis. Internal laying and EYP are very common in older hens and can affect walking, eating habits, and overall health.