I understand you are worried about him. That worry is compounded by the trip and the feeling that you are helpless. It's awful feeling like that, but you need to take a few deep breaths and try to relax a little.It's easier to think then. First, you need to determine if he is or isn't eating and/or pooping. The answers to the other questions will all be determined based on what results you may find when you isolate him.Sometimes there are no easy answers, but we will all try to help as much as we can. Do you have someone coming to watch the chickens while you are gone? Talk to that person about your concerns, so they can keep a closer eye on him.