For months,every night i feel my food coming back up&i feel nauseous.have seldom chest pains.endoscopy completely normal.y does lying down cause this?

? reflux: which is simply the travel of stomach contents upwards due to an open gadtroeophageal sphincter (the junction between the esophagus and the stomach), there are several causes for this: fatty foods, caffeinated beverages, overweight, and others, endoscopy can still be normal though. At any rate try to avoid / correct common causes, use OTC antacid as needed, see your doctor again for follow up