Hi maheswari,
I have had problems with sinuses up to 5 times a year. I found fasting a few years back, that helped me a lot. When I start to feel like having sinus problems, I start to fast. I just drink water, and after 3 days it is gone (usually it would last for 5-7 days).
While it lasts, I know that I still have it because my sinus is swelled up, but I do not have any mucus because of the fast. So it was symptom free (for me) almost. This last year or two I did not have problems with it, so my memory is maybe a little off, but I think it was (almost) completely symptom free.
Anyway, there are traditions in which fasting is recommended 2 or 3 days before both full moon and new moon. Didn't ask why while I was in one, but it is starting to make sense with your post and Shanti's in another thread. Back then it was just a chore to be done.
PS: Just to clarify, I do not fast unless I feel like it. Definitely not doing it every other week. Just a couple of times a year. Mostly in the summer, in the form of raw food diet.