Give a calcium tablet each day she is still prolapsing. Moist heat is helpful, but a soak can cause extra stress she doesn't need. You can use filtered water or distilled water to spray on her vent area to keep the prolapse moist. It shouldn't be allowed to dry out.
Too much protein over a long period does cause chronic issues and should be avoided, but in small amounts two or three times a week, it won't hurt. Animal protein is great for putting weight back on. You won't be doing it for more than a few weeks.