I lost a hen a couple of weeks ago, she was just standing looking very sorry for her self, had yellow/white diarrhea around her rear end. Crop was empty. In the end we had to put her out of her misery. Now two weeks on another hen is going the same way. Can anyone help me as to what this might be and what I can do about it? A friend of mine says it has been steadily going through her flock during the summer. So far the remaining 3 birds are fine, but don't want to lose them too.