A 20-yeаr-оld femаle cоllege student presents with nаusea, nоn-productive cough x 5 days, fever, chills, body aches, nasal and chest congestion, and nausea. She has a temperature of 103.5oF oral and appears fatigued and flushed, has an erythematous posterior pharynx without exudates, and clear lungs. What is the most likely diagnosis?