Thank you for the additional information.
You are correct to be concerned about the pancreas, and the other common cause of pain on the left side of the upper abdomen would be an acid irritation syndrome, such as gastritis or ulcers.
There would be more of a concern about pancreatic disease if there is more significant pain or tenderness. Although the ultrasound may detect certain problems with the pancreas, the usual first test to assess the pancreas are pancreatic blood tests, amylase and lipase.
The usual approach to a possible acid irritation syndrome is to first try a course of medicines to suppress stomach acid, such as Prilosec or Prevacid. If this is successful, then no further evaluation or intervention
is necessary, but persistent symptoms would warrant further evaluation such as an endoscopy or a test to look for an infection by a specific germ that is a common cause of a stubborn acid irritation syndrome.
Therefore, if the ultrasound is normal, it would be appropriate to have the pancreatic blood tests performed and to consider a trial of a medicines to suppress stomach acid.
If you have any further questions, please let me know.