If you think it is plugged sinus related I have a suggestion nobody has thrown out yet. Try drinking a teaspoon or so of Tabasco or similar hot sauce. Or even a good wasabi. I used to have bad sinus problems. My then gf told me that someone had suggested that for her ex. It worked for him, and it worked for me too. It seems to open up the sinus passages temporarily. Drinking the hot sauce then irrigating may be the trick.
"It is usually futile to try to talk facts and analysis to people who are enjoying a sense of moral superiority in their ignorance." – Thomas Sowell