I don't want to frighten you in any way Tia but my lovely mum had chest pains for about 6 months, the doctor didn't know but thought it was indigestion, she knew it wasn't as she kept talking about it. She died from thinning of the arteries several weeks later.
I would go with her back to her doctor, even take a man, sometimes that shivvies them up a bit and say you would like her to have an ECG to check things out, just as a precaution. It won't hurt and she will be comforted more and you knowing that you have pushed for more. I wish I had. It may of course be absolutely nothing to worry about but please check. Does mum smoke?