I must be missing something? Why would you give her antibiotics? I may have missed it, but I thought she managed to get the egg out. The worry with giving antibiotics if they are not needed is they may be less effective when you do need them.I have used Amoxicillin- 250mg twice a day for 7 days for Sharpie when she had her retained egg issue.
I also gave her 1/2 a low dose aspirin at night for 5 days, for any further issues with inflammation.
Sorry if I have misunderstood the situation.