Actually, those can be symptoms of a heart attack, particularly in a female, but the tests done in the ER may not immediately reveal the problem.
Several years ago, my mother had the same sort of symptoms, but the ER tests did not suggest or confirm a heart attack. She was quite sure it was a heart attack, however, and she was admitted to the hospital as a precaution. Two or three days after admission, blood work confirmed an elevation in cardiac enzymes which indicated some damage to her heart muscle, indicative of a slight heart attack. However, at no time were there changes in her EKG. The cardiac enzyme elevation was considered more reliable in determining what had occurred. Slight heart attacks can be missed on ER evaluations.
You can read about cardiac enzymes here
A few months prior to the above event, my mother had had a chemical stress test, rather than an exercise stress test, to evaluate her complaints of pressure in her chest. That test did indicate an area of some arterial occlusion, but my mother's doctor (an excellent cardiologist) questioned the test result, and did not think the situation required further action at that point. After her slight heart attack, the one noted above, she had angiography and angioplasty and a stent was inserted in the artery that had shown blockage on the earlier chemical test (the artery was 70% blocked). Whether that artery had been the area where her slight heart attack occurred was never determined, but she has had no recurrence of the same constellation of symptoms--jaw pain, shoulder and back pain, and chest pain--since that time (almost 8 years ago).
Hopefully, your mother's stress test will either shed more light on the problem, or rule it out as being of cardiac origin.
Gallbladder problems, and gallstones, can sometimes produce pains quite similar to a heart attack.