As I am not involved in your father's care, I am afraid that I cannot answer the question that you have asked. However, he should probably have an upper GI series ("barium swallow") to further assess the function and anatomy of his esophagus. (If this is not helpful, then a CT scan of the abdomen and pelvis may also be considered.)
I hope that his doctors will be able to identify the cause of his problems, and that they will be able to help him.
Sincerely,
Robert A. Wascher, MD, FACS
www.doctorwascher.com
Author, "A Cancer Prevention Guide for the Human Race" (2010)