It's normal to feel desperate and helpless when you have a chicken with a serious ailment. It's depressing and discouraging when your loved pet doesn't respond to your attempts to help. All you can do is force yourself to keep doing what you're doing, but prepare yourself for the eventuality that the treatment may fail. You do need to be prepared to end the suffering when it's obvious that nothing's working. It's the most painful part of this whole thing.