What Causes Irritation In Nose And Throat?

Hello Im a 36 year old male.Im a smoker and have been for around 15 years.Went to the doctor got blood taken all came back ok.My throat has benn killen me for over 2 weeks.Went to a throat specialist who ran a camera thue my nose to look at my throat and said it only appeared irritated.Started a steriod pack yesterday still no relief getting worried at ideas