mrcem2-0257

mrcem2-0257

A 3-year-old child is brought in by his father complaining of itchy skin on his arms. He has a history of allergies, and over the past few days, both of his arms have become covered in small red bumps. His father also reports that he has had a low-grade fever of 37.8°C. During the examination, you observe significant swelling of the lymph nodes in his neck. While speaking with his father, you notice a scabbing sore on the right side of his mouth.

What is the SINGLE most likely diagnosis?