I Used To Work For The Railroad And Coughed &

I used to work for the railroad and coughed & hocked all the time. The RR doctor said I was okay, but I have since retired and I still am coughing and hocking, taking cough meds, but nothing has helped. I worked around all kinds of chemical plants on the railroad, from town to town, state to state, is there a chance I could have asbestos disease or anything relating to my problem?