What Else Can I Give My Toddler For Spreading, Itchy Hives After Finishing Amoxicillin, Since Benadryl And Zyrtec Aren’t Helping?

Hi, my son is 3 years old. He developed hives all over his body after completing the Amoxicillin course for ear infection and severe cough. I ve been giving him Benadryl 5ml every 6-8 hours but it doesn t seem to help him as he s waking up crying due to severe itchiness. The hives seem to have been spreading more rather than reducing. Is there any other medication I can give ? He s been taking Zyrtec for allergies too.