I am a twenty one year old male that has problem during exercise and boxing in which I tend to gag when forcefully exhaling air through my nose and/or mouth (like when you exhale when punching in boxing). I get a sensation to gag and it happens whether I have a mouth piece on or not. I noticed this started happening when I started smoking cigarettes three years ago. One day I was smoking and I started gagging on a cigarette when I was blowing the smoke out of my mouth. I also had problems with constant burping and nauseausess due to smoking. I have since stopped smoking cigarettes for over a month through the use of commit lozenges and have tried the new NJOY ECIG. My stomach pains and burping have gone away and I noticed the gagging has subsided but is still present with intense and long exercise. Do you have any idea what may be causing this, be it physical or mental, or maybe improper breathing? I notice I gag less when I breathe through my nose but it still occurs occasionally and its ruining my training sessions in martial arts. I would really appreciate some help. Ive been do a doctor and she said she didnt know what it was.