Generally the best way to distinguish heart or Gerd is to take something like Zantac a coupe times a day. Take the therapeutic dose of 150 mg twice a day...this may be a total of 4 of the OTC variety. If it's GERD there should be rather dramatic relief.
What you have described sounds more like costochondritis which can EASILY be caused by a long bout of vomiting. It can also be injury to your esophagus from the retching. THe first one will be my "official" guess.
Usually GERD does not hurt QUITE so high as you describe.
Try taking some Alleve...if it helps a lot, then the pain is likely from your chest wall (costochondritis.)
Aneurism: I had a blood uncle die from a burst abdominal aortic aneurism and they told me they worry about only the DIRECT familial line (parent grandparent sibling). An aortic chest aneurism is typically painless until the point where it begins dissecting and then the pain is usually excruciating and death almost inevitable. I worried about it too and the first echogram I had, I told them to check my aorta...it was normal.
Best way to check to see what kind of shape your esophagus is in is to endoscope it if you have health insurance.
Did they ever uncover what was causing all that nausea and vomiiting?