What could it be?

My grandmother has been having a pretty consistent cough for about 2 years now. She coughs up clear phlem. Other than the cough she is fine, no other symptoms. She takes procardia for a heart function that her doctor told her was no big deal. (5 years ago) Anyhow she went to her doctor and they said that she has fluid in her lungs and put her on fluid pills. She also went for her yearly echocardiogram and that doctor told her everything looked great and he said no fluid. In the past week her cough has become a little worse so she went back to her regular doctor and they said she still has fluid and put her back on the fluid pills. My question is, does this seem right? Or should she see a specialist. Could it be her heart causing this and if so wouldnt her doctor that did the echocardiogram know this? She never smoked but lived with it for over 50 years. Any advice would be great thanks

[CCF CARDIO MD - DLB]

A normal echocardiogram makes heart failure an unlikely cause of fluid in the lungs. It would be worthwhile to see a pulmonologist (a lung doctor) for further testing; he can then rule out any serious cause of the cough.