My Son Who Is 18 Years Is Having Sinusitis Problem.

My son who is 18 years is having sinusitis problem. Ever since he has shifted to a hostel in Chennai ( warm ) from residence in Pune ( mild cold) his problem has aggravated. Often he gets a blocked nose , head ache ( temple and frontal region and cheek bones ). He often feels drowsy. He is also allergic to dust. He is adement he will take as less medication as possible. What should he do? offlate he has been prescribed nasivion.