michelle,
That is the definition of a hiatal hernia. Where the stomach slides up into the chest cavity, through a small hole in the diaphram. However, this hole is actually supposed to be there. It is where the esophagus travels through to hook up with the stomach.
But, in some cases, it enlarges a little, allowing part of the stomach to slide up. Some of the symptoms of a hiatal hernia, can be similar to GERD or ulcers.
So, if you think this is what is happening, then you should see your physician about it. This time, get your doctor's attention, and explain what you are feeling, and that you feel it may something other than ulcers.
Good luck.