I would suggest a liver panel, blood tests for H Pylori (a bacteria associated with
ulcers and inflammation of the stomach),
and amylase/lipase for the pancreas.
For non-invasive imaging, an ultrasound can be performed to evaluate the gall bladder.
However, with your age (50), I would strongly suggest an upper endoscopy. Although not quite non-invasive, this would be the most definitive test to make sure there is not an ulcer, inflammation, or cancer that is causing your symptoms.