My Doctor Can't Figure It Out. For Months Now I

My doctor can't figure it out. For months now I cough up this clear, sticky stuff. It's hard to breathe and occurs as I begin to eat. It seems to stimulate something in my lungs or esophagus. An air bubble and can't go up or down. It hurts a lot. If it happens to go up, anything I have in there comes up. It has been diagnosed and treated as a stomach problem. But, I only throw up if it lasts a long time. Sometimes, I end up throwing up my whole meal. On top of it I am diabetic. My blood sugar has been low, lately. And, I never know when it might happen. Help!