Hi and welcome to HCM,thank you for your query.
most common cases are stomach disorders such as gastritis
but it may indicate pancreatic disorder as well so you need to rule this out too. So i suggest to do gastrosocpy and ct scan
of abdomen first and then you can plan further tests if necessary.till that try to change your diatary habits first and see will it help.
Wish you good health. Regards.