If you are having any unusual pain that could be heart pain you should seek immediate medical attention - like the ER. Women often don't have the same symptoms as men. My mom had pain only in her back from a heart attack.
Of course it could be GERD or a hiatal hernia too. I've had a heart attack with center of the sternum pain, and I've had a really bad hernia with exactly the same pain. You can't tell without a diagnosis. Sharp or dull doesn't make a difference.
At least call your doc right away. If you wait and it is a heart attack you are killing off heart muscle.