Hi. I adopted 5 chickens when we bought our house. A couple were 3 yo. Fast forward a year and one of my older ones has been lethargic for a few days and drooling today. She was a TS purchase from what the previous owner told me. No idea what her breed or exact age is. She’s extremely thin. She has foraged a little in the last few days and drank water. No injuries on inspection. I’ve massaged her crop as well as checked for an impacted egg. No signs there. I have her quarantined with vitamin water and food. I don’t know what to do. Any ideas?