get a skin allergic test done to find the allergen and avoid the allergen.  both food and aerosol. use of steroid nasal spray with fluticasone and azelastine will help. but will need to continue it for 2 to 3 months. along with thay oral anti histamines with montelukast has to be taken. before starting any medicine get the necessary blood test done like complete blood picture, serum IgE,  skin allergy test(not routinely advised though). get a ct scan of pns done after 2 weeks of treatment and further management is required can be discussed with an ent specialist