Also a teaspoon of baking soda to 4-6 oz of water! Drink it. That will help also!
Try slow deep breaths too. That helps me also
Sit up, try a little drink of milk, if you have any gaviscon or tums then tale that too. Its awful, I know, I had terrible heartburn fot the last few months of my last pregnancy, good news is it disappears at birth :) Try sleeling propped up, its not great, but does help a little.