My Son 13, Normal Height And Weight, Has Had Fever

My son 13, normal height and weight, has had fever for 4 days and is on Sandoz Clarithromycin 250mg for very sore throat having been finished 3 days of antibiotic. He's still feeling very tired, dizzy with headaches and fever repeatedly going around 103.5 in the afternoon. When should I take him back to the doctor? Can I wait until the antibiotic is finished? He started feeling headaches and dizziness 4-5 days prior to showing symptoms of sore throat.