I came home after 3 days to find one of my hens with her eyes crusted shut. She's lost a lot of weight and her neck is curling back. I got the crust off her eyes and got her to drink some water. She also has some bugs on her that are kind of transparent with a dark spot in the middle, they are oval in shape and maybe a third to half the size of a grain of rice. She also smells horrible, a kind of sour/sweetish smell. Are the bugs the issue? What are they, how do I get rid of them, what do I treat the rest of the flock with (they look OK right now, but so did she 3 days ago)? Should I use a crop tube to feed her? Any advice is welcome.