I have pain, in under heart area, after eating, i think it is pancrease (pancrelipase). why it could be? and how can i diagnose this symptom?

May be ulcer: Could be reflux, ulcer or gallbladder disease, probably not your pancreas. You can try Pepcid (famotidine) which is over the counter; this will help reflux and ulcer symptoms.

GERD: This can be gastritis , gerd or other GI issues like pancreatitis. I recommend seeing your pcp or GI doctor to begin work up and get you proper medications.