AKT-1610

A 27-year-old man urgently books an appointment at your clinic. He complains of left-sided facial pain and malaise that has been ongoing for two weeks. He mentions that his symptoms initially improved after a week, but then worsened again, and he now feels worse than he did initially. He has no significant medical history.

During the examination, you note a low-grade fever of 37.9 degrees, but all other observations are normal. Anterior rhinoscopy reveals a purulent discharge from the left middle meatus, but there are no abnormalities in the eyes or periorbital tissues.

What is the most probable diagnosis?