Is she a silkie? Has her prolapsed vent been pecked at? As said, keep the prolapse from drying out, and an ointment or honey will help to keep it moist until swelling goes down and the prolapse may go back in. Does it feel like an egg is stuck, or has she just been straining? A human calcium tablet given orally may be helpful. I would offer some fluids up to her beak. Keep her separated and away from flies until the prolapse stays in.