What Causes Burning Pain Across The Sternum, Stomach And Abdomen?

I have been having Abdominal burning/pain all the way up to the Sternum along with Abdominal bloating. I had an Abdominal Ultra Sound, Abdominal/Pelvic CT Scan which were both negative. I had an Upper GI performed last Thursday and now I am awaiting the results. I was put on a high Fiber diet when I initially went to the M.D. and I believe I have lost some weight. Is there anything else that can be done diagnostically? Thank you.