I had this 2 years ago. I was the same. A non-productive cough.. I remember it started as a cold and then I thought it was allergies.. It went on for over a year..
I would cough until my eyes would water and I could not catch my breath, sometimes, I would vomit.. It was frustrating and embarrassing..I started avoiding movies and concerts or made sure I had a big bag of cough drops and sat on an aisle seat so I could leave the room if I started the coughing. ..
Finally one of my best friends told me I needed to see her acupuncturist.
Now I will tell you, I am not into all of that new age stuff and usually my eyes glaze over when people suggest anything instead of traditional physician, but I was so desperate, I went..
She was what I expected a new agey kind of person. She asked a lot of questions and then she waved her hands over me. She placed her hands on my chest and told me she knew that this "dark thing" was in my chest and she could help. She did the acupuncture and gave me instructions to begin breathing deeper and blowing out long strong breaths. She said I had been breathing too shallow.. She also gave me some natural herbal drops to begin taking. She told me very soon I would feel relief.
On about the second or third morning while brushing my teeth I felt this strong pressure like something stuck in my throat, I breathed in (it was hard to do with this pressure) and then let out a long slow breath and I kid you not, this thing in my throat felt like I blew it out and from then on I did not have that cough! I was astounded.
I am sorry your mom has been suffering with this, I began to think it was all in my head..
The Acupuncturist name is Kay Streich ###-###-####