What methods are effective in improving post-nasal drip syndrome?

I had a nasal endoscopy at an ENT clinic and they said I had both adult rhinitis and postnasal drip.

It seems that the symptoms of postnasal drip started to appear a few years after fine dust arrived in our country.

My postnasal drip is so bad that I keep taking medicine and washing my nose, but it doesn't get better.
I wonder if I'm not doing nasal irrigation properly. They say that if you irrigate your nose diligently, it will get better, but why isn't it getting better for me?

I feel fine when I take the medicine, but after I finish taking it all, my throat hurts again and I have phlegm.

I think it's become chronic, and now I don't really get any results from ENT medication, so I don't go to the hospital much....
So, since I also have rhinitis symptoms, it seems like it's not getting better.

In particular, sticky phlegm sticks to the tonsils and cannot be expelled.
If you open your mouth wide and look in the mirror, you can see the phlegm right away.

 

 

This is weak, and the phlegm is usually much thicker.
Even on days when I'm feeling fine, there's always thin phlegm stuck in my tonsils.
I keep coughing because of the foreign body sensation in my throat, and even when I cough, the cough doesn't come out well, so my throat hurts and is like a Möbius strip.

It's really embarrassing when you sneeze in everyday life and phlegm comes out suddenly;;

Especially when I lie down to sleep, I cough and produce a lot more phlegm, probably because of the lying position.

As a result, the quality of sleep also deteriorates significantly.

 

 

I tried nasopharyngeal syrup because I heard it was good for phlegm, but it did improve my tonsillitis symptoms, but it didn't get rid of the phlegm.

Is there anything that is effective in improving the posterior nasal passages?

I heard that in some cases surgery is required, but it's not that bad yet, but I'm worried that I might need surgery if it gets worse.

I think there are many people who have postnasal drip due to fine dust, so I would appreciate your opinions and advice...!