Thank you for your query.
Your child is suffering from an abscess
Give him oral antibiotics
for 7 days.
Give him paracetamol
Apply antibiotic ointment to that area thrice daily for 10 days.
Maintain hygiene.Consult your physician.
Hope this answers your query.If you have any other queries kindly direct them to me.Wishing your child a speedy recovery.Have a nice day.