You are in the right place and make perfect sense. My DS 15 (as of 1 week ago) also had most flare ups with sinusitis. Dr. B found the sinus problem 2 years ago and has been our mainstay ever since. It has been a very long road for us, but DS is healthier than ever and I am hopeful he will continue to do well.
Keep us posted on your son's progress!
If you don't mind my asking, what treatment has been working for your DS?