My 4 month old hen was acting a little strange yesterday, but I just blamed it one the newly cold weather. But today she's incredibly lethargic and limp. She's had an impacted crop before and nearly died from it, but pulled through. So of course, that's the first thing I checked for. But to my surprise, her crop is COMPLETELY empty. She hasn't eaten all day, and now I think she might not have eaten yesterday either! I have no clue why she would stop eating, or how to help her. The rest of my flock are as greedy and energetic as always. Another this I noticed is that her breathing is a labored (not incredibly, but enough that you can see her mouth gently moving). I've just brought her in and put her on a heating pad. She won't eat or drink, so I'm using a dropper to give her small amounts of electrolyte water and mushed feed. Can anybody explain what's going on? How do I save her?