I have a pullet (one of 8) who seems to have a large blister on her chest neck area. She seems healthy in every other way. We noticed it about 3 weeks ago. Her "sister" pullet had grown much faster and is quite a bit larger and has more feathers. Any ideas what it could be or what to do, if anything? I was not able to get a phot but it looks just like a blister. Approx 2 inches by 3 inches. Not tender or red. All the others are perfectly fine. Thanks in advance.