A warm bath might help relax her so that the remainder of the egg she has inside may be able to come down. I have heard of people using a very well-lubed finger to check the vent for any fragments that might be pulled down and out (gently) but have never done this myself. If the egg did break inside her, the antibiotic is probably a good idea to help prevent infection if at all possible. Keeping her in a warm, dark place may help to slow down her egg-laying cycle and allow her time to expel whatever bits she has retained. Good luck with your girl, and keep us posted.