You have had a comprehensive evaluation for your symptoms, and I agree with the diagnostic approach.
Other tests to consider would be a 24-hr pH study to exclude GERD and an esophageal motility study to evaluate for motility disorders.
Regarding the lymph nodes seen on the CT scan, you can consider a surgical evaluation to see if a biopsy is warranted.
If the GI tests remain negative, obtaining a neurological workup can be considered, as causes here can lead to chronic nausea. Head imaging with a CT scan or MRI can be considered.
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 Pho, M.D.