My only info on the subject of sinus is mine got a lot better after I changed what I eat. I no longer need decongestants when I scuba dive and I always used them prior to the diet change. Used to use antihistamines spring and fall with the season. Have not used them in four years, which coincidentally was when we changed our diet to a low carb regime (which naturally cuts out a lot of certain starchy vegetables and grain products).

I can't say it will help anyone else, but I have no other explanation for my ability to avoid medication to solve my sinus problems other than diet change. Maybe what we eat (or don't eat) matters?