I'm not sure about her food. Regular food and extra protein like eggs or fish is good. It won't fix her issues, though. If she has egg material building in her oviducts, the penicillin may or may not fix it. If she has fluid/infection in her abdomen, it may be more likely to work. In either case, I'd do the penicillin. If you dont, she probably won't make it, though I've seen hens bounce back from the brink of death without treatment on rare occasions. The first time Ivy was ill, with Rosemary, they were both emaciated. We still gave Ivy the shots, though I know it's hard when they are so thin. Maybe the thigh might work if you can't get it in the breast meat. It's not that hard, just get a 20 or 22 guage needle and go in about 1/8-1/4". Penicillin is kept in the fridge so you'll have to warm it up before giving it and you push in the plunger slowly, so you'll need a helper to subdue the bird.