Hi again otter2154, I am still researching this lung mucous problem as much as possible, to try and determine what the causative factors could be. In an online article located at: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1440-1843.2012.02307.x
by TRAVIS YAMANAKA1 AND RUXANA T. SADIKOT1,2, titled "Opioid effect on lungs" there is an interesting discussion about Noncardiogenic Pulmonary Oedema (NCPE). Here is an excerpt, located on page # 257.

"While heroin appears to be the most studied, legal
opiates used in a more controlled setting have also
been implicated in NCPE. One patient following
laparotomy developed bilateral pulmonary oedema
twice during the same admission to the ICU, both
times resolving with switch from morphine to other
analgesics.31 Besides morphine, oral opioids
including methadone and codeine may also cause
oedema."

My husband and I have often wondered if painkillers could be the culprit of this confounding condition. This thought has always been in the back of my mind, because I am running out of answers! It would be interesting to know if anyone that suffered with this horrible, suffocating mucous problem, recovered after quitting the pain medication. If this could be the cause, we all need to know! Does anyone know of such a person? Thank-you.