I just wanted to correct a few things. "Stomach pain" is actually not a symptom of acid reflux. Some people may get heartburn lower down but true stomach pain indicates that something else is going on. Also symptom improvement when you stand up but worsening when you lie or sit down, happens for some people, but it isn't a necessary criteria for diagnosis.
Also stomach pain, and symptom improvement when you stand up but worsening when he lie/sit down.
Welcome to the gastroenterology community! The most common symptoms are heartburn, regurgitation, and trouble swallowing.