I have a young hen that has what I can describe as like a pocket of air (a bubble or something) on her chest. I can push in on it but when I move my fingers it comes back. She acts normal, shows no sign of anything wrong! She eats and drinks normally as well. Has anyone seen this before and if so do you know what it is? I really do not want to harm her but I also do not want her to have something that she can pass on to the other chicks. Thanks so much!!