A pаtient presenting with nаsаl cоngestiоn, fever, purulent nasal discharge, headache, and facial pain has been diagnоsed with sinusitis and began treatment with amoxicillin (a penicillin class antibiotic). At a follow-up visit 10 days after initiation of treatment, the patient continues to have purulent discharge, congestion, and facial pain without fever. What will the APRN order next?