Phlegm problem

I am 31 y/o male and having phlegm problem since last two years. It is mostly thick viscous and white in colour but its viscosity changes time to time. It doesn't come out of chest instead it seems to be coming out from the lower portion of brain and mostly excreted through nasal track. sometime it gets less viscous and sometimes more but it doesn't stop. I used some alopathic medicines but no vain as the remedy is temparary for a couple of days.

I had nasel terbinates glands operation a years before and after that I felt that there is a big cavity and this phlegm or mucus gets accumulate in huge and upon secretion the quantity is big. Whenever I take tea or coffee or hot food, I urgently need to go to washroom to excrete the phlegm through mouth and mostly nasal track. I am also feeling some sensitivity inside my nasal lining in the sense of little burning.

About my diet, I eat flesh frequently mostly chicken and beef. Bread and rice are also included in my diet but I avoid rice due to this problem.

Please help me out if some doctor can help me out. I will really be very much thankful to you.