Well, there are withdrawal effects, though I’d think you’re past those by now. The breathing is probably related to the weight. IIRC, studies show that people who quit smoking tend to gain weight; nicotine apparently acts to suppress the appetite and as a stimulant, and in any case smokers tend to wander around while they smoke. I’ve got nothing on the coughing, only that it might just be another flavor of respiratory distress. You may want to see a doctor about that.