I would be the last one to tell you this is not a heart condition if I didn't think there was a chance it was.
What I can tell you is the symptoms you are describing are nothing like what I felt prior to being diagnosed with a heart condition or since.
With me the pain/discomfort that I felt was never constant. It would peek and subside according to the level of activity I was performing. There were times that I would feel pressure when I was doing nothing but it would usually subside after a while. Nausea
also accompanies my episodes. Shortness of breath
and light headedness. The amount of food I ate also had a effect on how I felt. As long as I only ate until I was no longer hungry and didn't stuff myself I wouldn't get any dicomfort after eating.
Nobody here can diagnose what your friend is going through. Only a Dr who examines her can do that.
The only advise I am going to give is if for any reason whatsoever your friend starts to feel worse to the extent that she is having trouble breathing then do not ignore it and don't wait for any darn appointment. Go directly to a ER. If she has trouble funtioning on her own AT ALL call a rescue squad.
Do not hesitate. I don't know whether this is something serious or not but I truly believe (based on what I know and have experienced) that what you describe does not sound like it would be an issue with her heart. I'm no Dr though.
Wish her well from us...