I was just cleaning out the brooder and I noticed that this little guy has one eye shut. It doesn't appear gummy or injured, but he definitely isn't opening it. He is acting a little more sluggish than the others, but eating/drinking/pooping is fine. Thoughts? Is he sick or do you think another chick injured him? Is the sight in this eye gone for good? Is there anything I can do to help him? Thanks in advance!