Hello and welcome to healthcare forum.
As you mentioned that you got e.c.g. and 2 D echo done, and both were found normal you should not worry about any heart problem.
According to me you are suffering from gastroesophagial reflux disease. Start tab. Pantoprazole+domperidone
, avoid hot and carbonated beverages, sleep with head up position.
Hope all these measures will work for you.
Still the symptoms persist, you will require upper g. i. scopy examination.
Best of luck.