It also has to do with the weather. Recently its gotten very cold, and when that happens, the humidity in the air goes waayyy down.. The air gets colder, dryer, and harsher. So when you smoke, you are inhaling some of that air. In summer when the air is moister, that moisture helps to soften the smoke and make it less harsh. In winter, we dont have that advantage, the smoke is possibly made even harsher because your throat dries out waay quicker. This could be one of the factors contributing to your decreased coughing tolerance. i have the same problem