Thanks for query.
It seems that your son might be having Acute follicular tonsillitis
producing swelling surrounding tonsillar area and pain.
He would require antibiotic medicine like Azzithromycin and anti inflammatory medicine.
It is better to go in ER as there is likely of flare up of tonsils and spreading infection.
Meanwhile ask him to take Ibuprofen
combination tablet for temporary pain relief.
Ok and bye.