Developed phlegmy cough. visited doctor & dismissed as cold. persisted for 2 months, revisited & given antibiotics for sinisitus. no improvement. ?

Sinusitis: Greetings. This sounds like the classic presentation and evolution of chronic sinusitis. Saline nasal wash with daily use of a topical intranasal steroid is the best place to start. A prolonged course of antibiotics and then if no improvement then a CT scan of the sinuses and/or an intranasal endoscopic evaluation is in order especially since the antibiotics failed to resolve the symptoms.