Hello Downunder. Did you know that in Traditional Chinese Medicine the lungs are associated with grief and sadness? I couldn't help but associate your cough/lung situation with the fact that your mother died...what ties the two together is sadness. I know that pears are excellent as a lung tonic. You can bake pears with raisins in the oven and eat them throughout the day to help heal your lungs. You might also want to take deep deep breaths out in the fresh air...filling up your lungs and diaphragm with healthful energy...(feel your ribs and diaphragm expand horizontally, not vertically) hold it, then breathe out.
Yes, in reading your post again, I think your cough must be related to your mothers death. Take care of your emotions and then maybe your lungs and cough will heal...?