can you post a picture? it sounds like a prolapse. soak her in a warm bath for around 25 minutes then apply preparation H to help shrink the area. if it is prolapse separate her act fast before it swells more
you can TRY to place it back inside likely it will pop out again. keep trying to shrink it with the cream. it might be necessary to take her to the vet and get a purse suture in place to hold it.I hope this is helpful. you can look up prolapse in chickens and see if that's what it is
good luck to you. I hope she gets better. you can also give a antibiotic for secondary infection. give her a water soluble antibiotic put into her water. good luck.