20 Years of Chronic Coughing: Seeking Advice

I also have had a cough fir over 20 years now. Been tested years ago for asthma, Gerd, acid reflux, chest xrays, endoscopy and all fine. Diagnosed with idiopathic cough as nothing worked. Had breast cancer 3 years ago and now my lung has slight scarring after radiotherapy which has made my cough worse. Stand up, walking up a flight of stairs I will cough my guts up. In the process of trialling various inhalers which to date have jot helped. Had covid last year which set me back a bit just would like to hear other people's treatment if anything helps even a tiny bit I will try anything. I also bring up clear mucus when I cough. Thanks