It's a good thing she is going to her primary care doc, because there a lot of things that can cause nausea and vomiting, none of them good and most of them not in a cardiologist's realm. A good GP should be able to do a preliminary differential diagnosis and send her to the right specialist.
I do hope the appointment with the GP takes place very soon, because if she really is vomiting with these episodes, she will be dehydrated and her electrolytes are going to get screwed up. That can get serious pretty fast.
The clevland clinic has some interesting areticles on nasuea and vomiting. It appears to me that they consider nasuea the same as vomiting only without the risks of dehydration. I know you are looking for someone that may have dealt with this, but I read that heart issues, brain issues, kidney issues, actuall stomach issues and more can cause nasuea and or vomiting. Is she taking any vitamins that may be upsetting her stomach? Im not one to pull the anxiety card, but is it possible she is anxious or anything due to the loss of her husband? There is a free site called freemd.com It may be a dead end, but perhaps you can go through it and find something? I really hope she is better soon.
is she vomiting or just feels like it?