While eating food i feeling pain in upper abdomen below chest. no other problems. why?

Consider these...: If you're indicating your epigastrium (just below the ribs in the midline), then you may have peptic disease (e.g. ulcer, gerd, reflux) or contractions or delayed emptying of the gut in that location (stomach, mid-colon). Less likely (& appropriate to symptom duration, intensity, timing, risks) your gallbladder or pancreas may be sick. Best to get checked.