Hi Kris, It's a rollercoaster ride with this disease, isn't it? In my husband's case, when he displayed the same symptoms as your dad (after having almost complete gastrectomy and partial esophagectomy), a CT had shown that his cancer returned in his stomach with mets to the liver. He filled up fast, vomited and often felt as though the food was stuck. They started him on a regimen of Taxol (from the California yew tree) and he did well after that. Wait for the completion of the other tests, this may be just something minor that your dad is experiencing. Every patient is different and responds differently.
Good luck,
Diane