sinusitis
"Prescribed Clarithromycin to treat sinus, ear, throat, and lung infection (possible pneumonia).  After six days I feel much better. I had splitting sinus headaches and they have stopped. Still have congested sinuses and cough, but diminishing. No GI effects (no nausea, no diarrhoea). Nasty metallic taste in mouth, especially on waking in the morning, but I prefer that to the difficulty breathing. No hallucinations or nightmares, just very vivid dreams, which I actually enjoy."