A 7-year-old boy is brought to the hospital with a 1-week history of fever, cough, and severe mucositis involving his oral, ocular, and urogenital mucosa. On examination, he has a sparse vesiculobullous rash on his trunk, involving less than 10% of his body surface area. A PCR test from a throat swab is positive for Mycoplasma pneumoniae. Which diagnosis best fits this clinical picture?