The pain of "heartburn" is usually felt at ther centre just above the diaphragm. This is because the pain is caused by a reflux of stomach acid. I will explain this in relation to the disease called Gastroesophageal reflux disease
), this is a condition in which acid from the stomach refluxes into the esophagus
. An estimated 44% of adults in the United States report GERD symptoms at least once a month, with approximately 10% experiencing daily symptoms.Transient relaxation of the lower esophageal sphincter (LES) is the primary mechanism responsible for the reflux of gastric contents into the esophagus. The LES is a muscular ring at the lower end of the esophagus that opens to allow for the forward passage of food into the stomach and then tightens to prevent regurgitation of gastric contents back into the esophagus. A small degree of reflux is physiologically normal; such episodes are typically brief and asymptomatic. In your case, however, I doubt that you have GERD, and it is probably just a 'one-off' that could be relieved by antacids bought over-the -counter. Should this prove not to be the case, you would be advised to consult your doctor.
I add a link containing details of GERD.
Hope this helps