you could let nature takes its course. We have a RIR who had the most awful looking prolapse, hated the recommended treatment, and managed to dodge our attempt to (as we saw it) 'put her out of her misery'. Son took that as a sign we should let her be. After weeks of pasty bum, which she attended to very carefully, she produced an egg without prolapsing again. Since then, she has laid erratically, now about every third day, and the eggs are back to large size. She is a young bird (first egg laid 25 March; she prolapsed 29 April; started laying again 20 May). So it need not be hopeless. Fortunately the other hens did not peck at it; but isolation would have solved that. My advice: give her a chance to heal.