My favorite hen is extremely lethargic, slowly waddling if at all, very swollen in the abdomen, having trouble breathing. The area around her vent was crusted with gritty, hard waste pellets. I washed her and probed her vent. More sandy, white waste came out, then about a teaspoon of blood. I couldn't feel any eggs inside her, but I felt a lump about the size of a pea on the wall of her cloaca, half an inch in from the opening. This particular hen, one of four that I have, is fond of eating cat food (dry food, good quality from Costco). I don't allow it, but she sneaks into the house at every opportunity for a few quick pecks before she gets thrown outside. The other hens aren't having trouble, so I'm wondering if this could be what caused the problem. In any case, it's an emergency right now, and she's not looking good. Advice is much appreciated.