Chicken health

my sister noticed this on her vent feathers

she drinks water fine, eats sometimes when foraging but is much more scared of me than the other chickens are and stands or hides in the coop usually. Is she getting bullied/sick both? She runs away wheb one of the other hens come near. She doesn’t try to compete for food at all. My dad’s chicken but he won’t let me take her to the vet. I tried to feed her an egg but she wouldnt eat much of it.

shes usually hiding.

edit: taking her to the vet first thing tomorrow