A 11-year-old boy came to OPD with a "cold" for 20 days. Now he has fever of 39.2degC, purulent anterior nasal discharge, facial pain, anosmia, and a cough. Examination of the nose after topical decongestants shows pus in the middle meatus. What is the best possible diagnosis?
Brain abscess Maxillary sinusitis Streptococcal throat infection Sphenoid sinusitis