I have a mixed heritage breed chick, four weeks old, who developed a strange lump on the back of her head. I noticed it about a week ago, it was bare of fuzz and raised and hard, but normal in colour. Now it looks like it got scraped or something and has some scabs. I'm not sure what it is, if there is treatment, or if I should even be concerned. The chick seems to be acting normally and the others aren't bothering her. Any advice??