Shortlessness of breath ?

hello everyone. i am 18 years old, male. i have had an asthma attack once or twice before, but they werent so bad that i had to be hostipilized i think. when i get sick, like coughing a lot, my asthma then acts up, but otherwise, it doesnt ever act up even after strenuous exercise. lately though, since ive begun college, i have not exercised much at all. i have had two shortlessness of breath out of random/ sudden. what could be the cause? do i need to eat healthier or exercise more? im thinking it could be a lack of exercise but im not sure. also, i have no family history of anyone ping away from disease. none. we are all healthy, but of course, not me lately. i used to exercise in high school a lot now. but not much since the past 4 months. also, this occurs at rest, i was just sitting here wathcing a movie and it just happened once. it has happened once or twice before in the past 4 months. any one help?