I am surprised there are not more posts like yours.
Two years ago, I began coughing and bringing up a significant amount of phlegm. Since then I have seen 8 docs, have had six diagnoses and have undergone dozens of tests. The only thing they have determined is what it isn't. It isn't asthma, bronchitis or an infectious disease. All of the docs commented about a potential connection between my IBD and problems with airway passages. Similar to the connection with having digestive tract issues and having Crohn's.