Alright, Chicken Ladies

So of course my favorite hen, Mary Anne, has been acting funny these last few days. She seems very lethargic, uninterested, depressed and just overall very confused. She used to run to the fence when she saw me coming but now she’ll just stand wherever she is like she’s never seen anyone or anything before. She seems to be eating a drinking just fine but I noticed a few days ago her comb was starting to sag along with the other symptoms I just listed. I found and killed a black snake in their coop a few days ago (the reason I was only getting 3 eggs out of 10 chickens) and I’m starting to wonder if maybe she got bit because black snakes will make people very ill. I don’t think she’s on her death bed but she definitely just seems all around sick. Any possible reason for this? Is there anything I can do to help her feel better? I’m already in the process of getting her some eggs scrambled and some applesauce in her.