Dear Grandma -
Have they ruled out angina? Women get heart-related pains that are not typical of most heart attacks. I have prinzmetal angina, which is difficult to diagnosis and only occurs in women (I was told by my Cardiologist). My pain is usually in the middle of my back, but it can also occur in the jaw. It is being treated with 2 nitroglycerin tablets per day, which has helped greatly in my case.
You might want to check with your GP and get an EKG.
Just a thought.
Jan D