Additional reply from the vet:
Force feeding can only be helpful. If you're adept at tubing a chicken, make a gruel of her crumbles and tube it into her until her crop appears to be half-full. Repeat tubings when the crop empties. Charcoal isn't indicated but a full physical exam including vent inspection would be ideal. If that isn't possible, is your comfortable gloving up and palpating inside her cloaca (vent) for an egg?
Force feeding can only be helpful. If you're adept at tubing a chicken, make a gruel of her crumbles and tube it into her until her crop appears to be half-full. Repeat tubings when the crop empties. Charcoal isn't indicated but a full physical exam including vent inspection would be ideal. If that isn't possible, is your comfortable gloving up and palpating inside her cloaca (vent) for an egg?