hi i had gone through your query and understand your concerns. i would come up with two possibilities,
-1.the first one include;ALLERGY
is the underlying cause for the development of your sinusitis
possible causes of allergy include;
DIET TO FOLLWO;
reduce sugar; which is an irritant to mucus membranes, although honey is good.
No white refined flour.
Avoiding frying foods which make fats less digestible to you
2.second possibility include,ACID PEPSIC DYSPEPSIA
may be the cause
without treating the underlying cause you cant be cured with any system of medicine.homeopathic
constitutional similimum ( but not symptomatic treatment like allopathy are you taking now,it is not useful for you )is the answer for you.
consult your local classical homeopath.
I hope this is helpful for you, thank you