I have something similar. I feel the breathing thing is anxiety, as I only have issues when I become aware of my breathing, take deep breaths and yes, the yawn thing. I can run 5k so there cannot be an issue with breathing, logically
I also have a post nasal drip, which has given me throat problems since January, medication for reflux and nasal sprays have not helped, so not sure what is causing it, although I have read an article which links it to the menopause. See if you can find the thread Menopausal phlegm in other health issues