8 nth old ear infection came back allergic to penicillin, took 2.5 ml azithromycin 5 hours ago now he has 5 red areas with white middle. allergy?

Could be allergy: He may be allergic to azithromycine as well, have it checked by your pediatrician.

Workup and follow up: The two antibiotic classes are distinct, but it may be possible for a baby to have allergic reactions to both or either medication. Typically an allergic rash looks blotchy and is itchy. If there are other symptoms including GI upset, breathing difficulties/drooling/problems swallowing, I would advise an evaluation in the ED. A follow up visit with your pediatrician is suggested.