I never stop coughing! plz help!?

for the past year i have had this cough. its a dry cough, and sometimes with phlegm.im always coughing even at night and i never get any sleep. i have gone to the doctor about 5 times and i have had strep throat 3 out of the 5 times! i have no idea what it is! i have no fever, but i do have chills. i dont have the time or money to go to the doctor again and hear the same thing! could i have strep throat again, or could it be something else?thanx