i would continue giving him benadryl and ice it. this can be several things:
an allergic reaction
an early viral infection (many have rashes called exanthems)
a sinus infection (can cause swelling around the eyes but less common at his age to have well developed sinuses)
i would call his dr if it gets worse on the benadryl today, he might need a stonger med like prednisone for the swelling, or if he develops a temp over 100.4.
otherwise id have him checked in the office tomorrow if not better.
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