There are many reasons for this condition to develop e.g. allergy, viral infection, bacterial infection, cough tendency of body (kapha prakriti), septum deviation and many more. These pathological conditions are treatable though it requires quite a disciplined approach from your side as well.
However one secret reason for sinusitis is psychological which none of the pathologist or medical expert will ever be able to tell you. That reason is - curbing your original passion in the childhood and settling for some other career (not of your liking) due to parental pressure. Many of those children who are coaxed to take up the career choices of their parent's liking and not theirs are prone to develop minor deviation in the nasal septum and suffer from nasal congestion. That is why I am always in the favor of finding your true passion before you settle in for your career. In today's world people identify careers with authority, money and fame associated with these and children being powerless succumb to undue pressures of their parents. And when child curbs his core desire it takes toll on his physiology and poor child suffers through his life.
Analyze yourself and identify the exact reason for your sinus problem and if you find the root cause to be psychological then even surgeries are not going to help. The problem shall recur despite surgical correction. However don't panic 'Tattva Shakti Vigyaan along with Shakti Healing' does have a solution for such cases. For pathological types ( do ascertain the reason for your sinus before trying to treat yourself) which are due to cough tendency of body, improper diet and routine, allergy etc. following can be tried -
1. Sleep early and get up early. Sleeping till late in the morning causes polyps to swell.
2. Improper or insufficient sleep increases the chance of allergic reactions in the body. Nasal cavity and lungs and eyes being the most vulnerable (due to direct exposure to outside environment) are affected the most.
3. Boosting your immune system is necessary to deal with this issue and for that you should have variety in food and also cut down on the food items which cause cough tendency for example yogurt or dahi in the night.
4. 10 minutes running after proper warm up shall help in bettering the blood circulation which shall wash away the toxic built-ups in your facial tissues.
5. Drinking warm water is most appropriate for sinus patient. Of course this also implies you should not have colas, beverages and icecream etc.
6. Nadi-Shodhana for 10 minutes and sarvaangasana for 2 minutes will help improve blood circulation in facial tissues thus reduce the problem in longer run (initially you may see worsening of the problem - don't worry and don't give up if it happens however ensure that the breathing rate is extremely slow.)
7. If you are not allergic to honey and shilajeet do take it along with milk everyday. As such people suffering from sinus should avoid milk without adding anything to it. If you are allergic to the above two things you may add one TSP of ground turmeric (powdered haldi) with milk. Always consume warm milk.
8. Avoid exposure to sudden temperature variations. And if you are accustomed to AC sleeping - make sure its temperature is set closet to the body temperature i.e. 27 degree Celsius.
9. Learn jal-neti first as sootra-neti would be bit difficult and may hurt your inner nose (if not done properly or done in haste). Mix one TSP common salt in one liter of lukewarm water and do jal-neti regularly with it.
10. Wash your face with warm water two to three times a day and do not apply too much pressure while wiping.
As I said earlier the expert advice must be taken to understand what type of sinus problem you have but if all the above things don't work you must check with doctor. Don't delay it as this may be caused by some other issue.