David, 13-year old male presents to the Emergency Room with his mother complaining of sore throat. He describes a sudden onset of sore throat 2 days ago. He has been feeling more tired then usual and now has trouble eating or drinking due to the pain in his throat. He denies any coughing or runny nose. David has no known allergies to any medications.

General appearance: Overall well fatigued looking 13-year old boy
Vitals: HR: 96 beats/min, BP: 110/66, RR: 17/min, T: 37.4 C
HEENT: Erythematous tonsils, normal tympanic membranes
Neck: Tender cervical lymphadenopathy
CVS: Normal S1, S2
Pulmonary: Chest clear to auscultation
Abdo: Soft and nontender.
Neuro: Screening exam normal.

What is your differential diagnosis at this point?