A nasal decongestan helps with my congested nose. You can get them OTC. Irrigation is done to keep your nasal passages clear. It's like spraying a solution into your nose. It can be done using a machine or just a bottle.
To make a very long 32 year story short: NasalCrom has rescued me from terrible sinus headaches for 32 years. A doctor once told me I have "asthma of the sinuses." And he was right,because NasalCrom is asthma medicine in a nasal spray form. I only wish I had NasalCrom for the past 32 years instead of constant antibiotics and millions of pills. Oh well - better late than never! It's cured me from my dreaded headaches by about 95%. I wish you all could find a miracle cure like I did.
Many saline nasal sprays contain a preservative that can irritate sinus tissue....best thing to do, is create your own nasal spray using kosher salt and distilled water.
You can get a list of the preservatives from the internet even if they are not on the product's label. You can also get much better and more precise 'recipies'. I use Ringers/Loehs solution which is available commercially but at high cost, so I now make my own. Again there are lots of formulas available that aid you in creating a biologically in-active wash that does not cause any in-flow or out-flow of ions from the nasal tissue.