There are a variety of reasons for
upper GI
pain after eating, including, GERD, an ulcer, or inflammation of the upper digestive tract.
I would consider an upper endoscopy, or upper GI series, to evaluate.
If negative, a CT scan or ultrasound can be considered to image the liver or gallbladder. If the pain localizes to the upper left quadrant, the CT scan would be able to image the pancreas and spleen as well.