I would just use a mild oil or honey to keep it moist. It almost sounds like she has a blockage of an egg or lash egg that is preventing her from pooping. This is pretty far along, so I wonder if she can be saved. Is a vet possible? Is she eating or drinking at this point? Is she in pain...
Can you give her some calcium or Tums right into her beak to swallow? That may help the prolapse. I would soak her in warm water with salt dissolved 2 tsp per quart, or Epsom salts for about 15 minutes, as long as she is not too weak. Try to feel for a stuck egg. Then dry her with a warm dry...