hi.abdomen is a junk box and cause for abdominal (stomach pain) can be anything from gastroenteritis
to intestinal obtruction pancreatitis
etc etc. but they may also have varied associated symptoms.
yours pain looks non specific as it is not localised to one particular area.
if the pain is very severe please go to the emergency room and get examined by a surgeon as that will determine the exact cause depending upon the clinical signs and investigations if required.
so hurry up.
all the best.