Jill, UK

I too have a persistent cough but was diagnosed after 2 years, having had all the lung x-rays, ENT camera, allergy test, asthma and breathing tests etc.

Have you had a gastric- endoscopy to check for a Hiatus Hernia? You don't need to have heartburn or acid reflux to have a hernia. The problem of the cough is when the diaphragm pushes against the stomach when you are lecturing or sitting especially if leaning over, exercising etc.
This will push the acid out of the stomach, which tries to seep into the lungs, mucus is formed as a protection and then you have the cough.

My cough will start when I am singing, giving presentations, sitting down in a slumped position, bending over to pick something up. I am also unable to sleep on my right side or flat in bed.

Hope this helps.