I used to smoke crack, I quit 2yrs ago, but since I quit, I am still coughing up clear mucus with black specks in it. Sometimes more than others. I do have asthma and I have been worried since this wont ease up. I think 2yrs is a long time for my lungs to be still trying to clear out the damage of crack smoking!!! Should I be really concerned?? I dont have any shortage of air or discomfort!! PLEASE HELP!!!