This is very probably from the stomach, maybe "hiatus hernia". It's not "critical" in the sense of being life dangerous, but you should have this checked by your primary doctor and then gastroenterologist. Such a hernia can cause leaking of acid from the stomach into esophagus, what can damge esophagus.
You should see a doctor.
It could also be your xyphoid process. Is it a small lump of bone sticking down off the bottom of your sternum (breast bone)? The xyphoid is supposed to be there.