Acid reflux, or commonly known as heartburn, is a burning pain in the part of your chest, usually in the area of your heart (That’s why it got its name!). The pain is stinging and burning, beginning at the breastbone then towards your throat.
Heartburn occurs when the acid in the stomach backs up to your esophagus. Regularly, sphincters, a band of muscles, keep stomach acid from back flowing to your esophagus. However, there are times when this muscle weakens or abnormally relaxes, allowing stomach acid to reflux and cause heartburn. That is why lying down or bending over may cause heartburn.