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Your 4 year old son is suffering from otitis externa
and interna ( Infection and Inflammation of Ear)
do not poke ear with cotton swab as microabration is common .
Consult an ENT Specialist
to look inside ear canal
for any pus discharge if so send Pus for Culture and Sensitivity to nearby Lab and Start on Sensitive reported drug to get speedy recovery.
Child will not say any complaint to parents or doctors .We should be aware in the childhood stage .
I Hope I Provided Useful Information. Do ask Furthur Questions to help You get well soon.
Dr.J.Kingson John David