RIGHT ARM PAIN AFTER EATING

My dad has right arm pain after eating. It starts in bicep and spreads to thumb and then radiates up in chest and jaw. Three days ago he had two discs replaced in his neck, four bone spurs removed, and two pinched nerves released. This was all done in his neck. He is now saddened because after eating only two bites of ice cream his severe arm pain has begun again. What is happening? He has suffered with this four years and has had many tests run and xrays. Doctors do not understand the pain with connection to eating. he didn't suffer neck trauma four years ago. At that the beginning, he started having severe pain in his right arm after eating. He made several trips to the emergency room and could not find anything wrong. His heart is fine. His esophagus is fine. His gallbladder is working. One hospital said he doesn't have gallstones and one VA hospital said he did. He does not have intestinal problems like stomach pain or nausea. He bowel movements are normal except for constipation every once in a while due to pain pills. If anyone can help us we would appreciate any replies.