I am 16, almost 17, and for almost 3 years I have had excessive mucus in the throat, with a persistent cough that leads to dry heaving and sometimes vomiting. Sometimes the mucus is so thick and sticky that it blocks my throat and almost suffocates me. I have tried allergy medication, cutting out dairy, sugar and gluten, and nothing works. I don't smoke, but people say my cough sounds like a smoker's cough. I've been to see a doctor several times and they give me antibiotics, and I take them but it doesn't make any difference. I think I may have asthma. I've never had an asthma attack but I sometimes have wheezing, chest tightness and shortness of breath, but my dad says if it was asthma then I would've had an attack by now. What could it be?