Hi, My 16 Year Old Son Was Prescribed Cephalexin For

Hi, my 16 year old son was prescribed Cephalexin for Impetigo and an ear canal infection but now he is getting hives.( I am not sure it is from the Cephalexin) I gave him Benadryl and the hives are gone. He has never gotten hives before while taking the medication. But I am still concerned. I am planning on taking him back to the Dr tomorrow. Is there anything else I should do?