My Son Experiences Cough Spasms, Inside Of His Nose Swells Shut, Throat Tickles, Itchy Red Welts Appear On His Back

My son experiences cough spasms(coughs that lasts for hours, days even weeks at a time) that are quickly brought on by an allergic reaction. This occurs in months of Aug. Thru mid April. Each month at any given time Zac will take an instant breath and all of a sudden his inside of his nose swells shut, throat tickles, itchy red welts appear on his back,and a cough spasm that continues non stop for hours, days, even weeks at a time. This first episode occurred this week and this time zacs face and lips swelled along with difficulty breathing this occurred 3 days after zac was into his coughing spasm. I am wondering if this is an anaphlactic episode that my son has to pollen or seasonal allergies?We need some answers because the doctors around here have never seen anything this sever with a cough and keep treating it with antibiotics , breathing inhalers and allergy pills. The cough spasm stays until at some point in time stops. Please help us help our son. I am tired of watching him suffer! Jennifer