She's probably a heavy smoker. I smoked two packs a day for 33 years. Quit on a bet when Pres Bush beat John F'n Kerry. I had a constant cough for the last ten - fifteen years as a smoker. I didn't even notice, as it happened gradually, but I would cough and hack myself to sleep and wake up the same. Horse and choking a lot. Since quitting; I do not anymore.
I rarely choke or cough now. I do notice that.