Suggest Remedy For Cough Due To COPD

Good Morning Dr. Grief. My husband David (DOB 5/29/43) has COPD, Parkinsons, RA,Fibromyalgia, and has been given for a cough which he has almost all the time heratussin AC. I ve just gotten on the computer and found that someone with COPD should not take this medication. His doctor has him on the nebulizer three times a day (he was on twice) and this cough medication. He is VERY prone to pnemonia or broncitis (?) whic is part of COPD. He was told this by the doctor. He s been in the hospital three-four times with severe pnemonia. No x-ray taken to see if there is any thing in the lungs, he coughs horribly and cannot bring anything up very often. What can I do to help. Thank you.