Years of blocked nose and cold and allergy symptoms

Patient: Since I can remember I have always had a cold, a blocked nose, symptoms of allergies. Having been to my doctor countless times over the years and been given advice to take vitamins (which I already do so), prescribed nasal sprays, anti histamines etc, nothing helps. I have now had this cold for 2 and a half months. I cannot breathe through my nose at all.I have sneezing fits that are so aggressive I have pulled muscles in my back. I cannot smell, hear or taste properly. I am at the end of my tether. Have you any advice?