I have a hen that is about 3 years old. I have noticed the past few days she has a messy vent when she has never had this problem befor. Today when I let the chickens out I noticed that she had layed down in the grass in the yard. This is very uncharacteristic of her. When I approached her to check on her she got up very slowly. I picked her up and could smell a nasty smell coming from her mouth so I opened her beak to look inside and that is surley where the smell was coming from. She is not walking or standing funny but she seems somewhat lethargic and a little disoriented. What am I dealing with here?