How to heal too much acid in stomach?

Not sure it's acid. Heartburn is a symptom that develops when stomach contents reflux into esophagus. Acid is a common cause of heartburn, but alkali, bile, regurgitated caustic ingestion, medications, food, pepsin, etc. Are all non-acid substances that can also irritate the esophagus ; cause a "heartburn"-like presentation. Consider also delayed stomach emptying, stomach outlet narrowing, esophageal dysmotilities.