Thanks for writing to health care magic.
Swelling of the cheek could be because of mumps
. A physical examination by your doctor will help in the diagnosis. MMR vaccine
given at the age of 15 months helps in prevention of the illness.
In a child with mumps symptomatic treatment and monitoring is is required. Isolation of the child is important as this is a communicable disease.
Do not send him to school if the diagnosis is confirmed.
Continue to ask further queries as required.
Hope this helps.