Sore throat at night from last 8-9 month

Hi, I have sore throat at night from last 8-9 months, though its not daily but yes it exists, i did chest and nose xray 3-4 months ago but everything was clear, i also did blood test on kidney, liver, ige and etc but all were clear except the ige level to 400 which is allergic m In sputum test klebsiella pneumoniae bacteria was detected for which doctor told me to take ceftum for 10 days, which was somewhere between august 2019. I dont have any other problem like breathing or cough etc beside normal cough on cold. What can be reason of sore throat, is it like post nasal dip etc ? Cough and mucus seems normal, its just little sore throat feeling, which last half/1 hour based on time. Is it something serious. Thank you.