Hello,
I suffered from heartburn terribly when I was pregnant; it was ruining my life!
I don't remember what it was called, but my GP gave me some stuff for it, which worked brilliantly. It stopped the heartburn almost instantly after taking it. Even better, because the GP dispensed it, it was free.
The one thing about it, though, was that it made me constipated. Heartburn or constipation. You choose!
Good luck.