You are completing an elective at an urban pediatric ambulatory clinic. Your preceptor asks you to see Hanna, a 28 month old female. You introduce yourself to Hanna and her mother, and learn that for the last two days Hanna has been having a runny nose, coughing, and complaining of a sore throat. Over the last two days Hanna has become increasingly fussy and is eating less than she had earlier in the week. You perform a physical exam and find the following:

General appearance: Quiet and shy, does not appear toxic 
Vitals: HR: 96 beats/min, BP: 105/66, RR: 23/min, T: 38.4 C 
HEENT: Erythematous tonsils, normal tympanic membranes, coryza, rhinorrhea, conjunctivitis 
Neck: Tender cervical lymphadenopathy 
CVS: Normal S1, S2 
Pulmonary: Chest clear to auscultation 
Abdo: Soft and non-tender, no masses 
Neuro: Screening exam normal

Which of the following are on your differential diagnosis at this point?