Have you been tested for Pertussis (Whooping Cough)? I went through a 3 month ordeal a couple years ago with a horrible cough that left me unable to breath frequently. After many many doctor's visits and treatments, it turned out I had multiple things going on at the same time.
1st--I had a sinus infection. Put on a couple rounds antibiotics in addition to my 4 allergy meds I take year-round. Developed cough that they thought was just caused by PND.
2nd-cough continued. They increased my allergy med dosages a couple times. I ended up on Singulair, Advair 500/50 and Albuterol. Went on a couple rounds of Prednisone. (I don't wheeze with my asthma either.)
3rd- cough continued. I went in for testing for silent GERD. Endoscopy showed nothing, but 24 hr PH confirmed I had GERD with coughing as my main sympton. Changed from once a day Protonix to twice a day Prevacid.
4th- Cough continued--I caught a virus and lost my voice and got the flu in the same week.
5th--received my third test for Pertussis. The first ones came back inconclusive which they attributed to having received the vaccine when young. The last one came back indicating that I had probably caught Pertussis early on. They figure all the antibiotics I was on for the sinus infection had treated the Pertussis. The cough remains even after treatment. It is nicknamed the "100 day" cough.
I can tell you I was thoroughly worn out during this entire time. One day, after about 3 1/2 months, the coughing just started decreasing in frequency.
Throughout this process, my doctors explained that there are several main causes of chronic coughs. (I did internet research to verify this.) Turned out I was dealing with all with a cough as my primary symptom. They are:
- Post Nasal Drip
GERD/ Acid Reflux
They also like to rule out any concerns with the heart as well.
I hope you find something from my experiences that is useful.
Good Luck finding your solution.