I agree with the tests done thus far.
The negative CT scan and cardiac tests would make other causes less likely, including coronary artery disease or gallbladder/liver disease.
A 24-hr pH study can be considered if GERD is suspected, to quantify the severity. If GERD continues to be suspected, you can add Reglan or an H2-blocker like Zantac or Pepcid to the Nexium.
If the symptoms continue, surgical options may need to be considered. These options can be discussed with your GI physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
kevinmd_