Natti a 6 years old boy was brought by her father, the boy presents with a fever, cough, and a sore throat. On examination, the tonsils are erythematous but without any exudates. There are no palpable lymphadenopathy. He had 3 similar episodes last year which were self-limiting. He has a temperature of 38.3°C. The diagnosis of tonsillitis is given. What is the SINGLE most appropriate treatment for this child?