Here's another approach to sinusitis: humming.

In a study that was reported in the American Journal of Respiratory
and Critical Care Medicine (2002; 166: 144-145), researchers at the
Karolinska Hospital in Stockholm, Sweden found that nitric oxide
levels in the sinuses were 15 times higher during humming than during
normal, quiet exhalations. Nitric oxide (NO) helps to dilate the
capillary beds and increase blood flow. Humming had the effect of
dramatically increasing the gas exchange in the nasal sinuses. If
fact, during normal exhalation the gas exchange between the nasal
passages and the sinuses was about 4 percent. When the volunteers
(all "healthy") hummed, the gas increase incased to about 98 percent.

A poor exchange of gas, as well as poor circulation, in the sinus
cavities, creates an ideal environment for the growth of bacteria and
viruses. And this can quickly lead to infection and discomfort. Based
on the results of their study, the researchers believe that regular
breathing exercises that involve humming may be able to help reduce
the incidence of sinusitis and infections in the upper respiratory
tract.

Immune booster for sinusitis

Here is my cure for sinusitis. I lived in NJ for 30 or so years,
never suffered from sinus problem, moved to Houston for 16 years,
ditto, moved back to NJ and started getting sinus infections every
few months. Every time I had a cold, it turned into sinusitis. Each
episode was worse. I had to take antibiotics which made me sick (as
well as being devastating for our environment).
I read a book about Chinese medicine and discovered that sinusitis
can be a symtom of a depressed immune system. My immune system is
very depressed due to stress and big sleep deprivation. Then I
noticed that every time I had a sinus attack it was when I had had a
night of unusually little sleep. After reading the book I started
taking an immune booster every time I felt the slightest indication
of sinus problem. Amazingly, since I started this, a couple of years
ago,  I haven't had a single sinus infection!
What a relief.
[I take Esberitex by Enzymatic Therapy, which I am not promoting the
company although I like it. Esberitex is an immune booster available
from other companies. ]
Hope this helps somebody. Sinus infection is incredibly painful.