I had some problems with my son year ago. He had terrible cough
at night many years. His lung where clear and doctors could not do anything. They supposed allergy. I put the can under son's bed. That looked like sort of tissue. My brother(he lives overseas) adviced me to think of parasites. (I am agree with Bob). He told me that there are fungi or even worms could be.
I went to the health store and was adviced to take something for cleansing of lung. I do not remember how was called this remedy. Probably ASPIR- AID ? If you wish- igo to my health store and find it out for you. I saw this remedy (Liquid) in the other stores. Since this treatment my son never has a cough. Just visit a good health store and try to get the good brand - (it's important).
Also may be would be a good idea to use the common cleansing of your body suggested on this website.