She is probably sleeping and resting even though she is standing. It can take a couple of days for the laying to stop with the darkness. During the 8 hours of daylight, you could place her in a cage near the other chickens so she can feel like she is with them, but she won't get pecked. Make sure the prolapse stays moist with honey or oil, since
The prolapse tissue can become damaged and die if it dries out. If it has stayed in that is good. What do you normally feed her? Reducing the amount of feed or protein in it can help to stop the laying, but she needs more than just corn. Most feed stores sell procaine penicillin G in the refrigerated antibiotics, and syringes with 20 gauge needles. Dosage is 1/4 ml (0.25 ml) given 1/4 inch deep into the breast muscle once a day for 4-5 days, if you feel you must give antibiotics. Good luck, and I hope you can save her.