Doubt i have cancer but theres no other appropriate place for this question

I've had a cough for about two years now.
Ever since i was a child i have been exposed to second hand smoke but i never seemed to be sick from it. i doubt i have cancer.
sorry if i am posting in the wrong place, but im worried. i have a dry, throaty cough every once in a while, at least twice a day. its a dry cough, no mucose, no running nose. no hacking either...just some shaky breathes after a bad coughing fit. it shakes me up worse and worse as time goes by.. its really starting to freak me out. doctors say nothings wrong. people dont even notice my cough. but it happens everyday, for the past couple years.