My daughter is allergic to amoxicillin, what should I do she is breaking out into hives

Take her to her pediatrician/doctor. If she starts having difficulty breathing then take her to the ER. I am also allergic to amoxicillin and penicillin. The last time I had hives because of this, I faintly remember going on some kind of steroids or zPac. Something like that... but if she is truly allergic, then only a medical professional is going to be able to help.