Thank you for consult:
A – Antibiotics are generally not need in case of an allergic reaction. I assume that there is no pus collection, pus discharge, active wound or red eyes. If any of these symptoms are there then you might want to give her the antibiotics. If not then you can just skip the antibiotics and observe for the remission of symptoms. If in doubt, you better follow the Doctors recommendation since he/she has clinically assessed the patient.
B – Claritine and Primalan, both have more or less similar actions and profile. So you may continue with Claritine itself. Please make sure she is getting adequate dosage.
Hope this helps. Thank you.