A 28-year-old male developed chills and high fever after playing basketball in the rain, accompanied by myalgia, right chest pain worsened by deep breathing, and rusty sputum. He presented with an acute illness appearance and herpes at the mouth corner. Physical exam: temperature 39°C, pulse 88/min, increased tactile fremitus in the right lung, dullness on percussion, and bronchial breath sounds. Lab tests: WBC 25×10⁹/L, neutrophils 0.90 with left shift. The most likely diagnosis is: