Experiencing Pain In Upper Stomach, Below The Chest. What Could Be Wrong?

I am 42 yrs. I was experiencing pain in the upper stomach just below the chest .. mornings are usually fine.. discomfort appears before lunch time and after lunch.. on some days it continue till late evenings and after dinner I feel relaxed on most of the days.. however here were exceptions in the timings.. My doctor prescribed me Ganaton total(2 months, once daily empty stomach, oflomax TZ & Equirox( for 5 & 3 days respectively) ... i started the course on 15th feb 2013.. I was feeling nice.. Since day before yesterday I am experiencing some discomfort again.. Let me also convey that I had a piece of a big fish the day before yesterday .. otherwise I had been taking mostly veg meals.. today in a plan to avoid roti, I took a rice meal at about 9:30 am.. of course after getting up from bed except water I took nothing.. today i started feeling discomfort immediately after the rice meal and it is continuing even now.. its 2:30 Pm now.. sometime ago had a light meal of kichri in office itself.. i wonder if remaining hungry after getting up for 3 hrs is a reason.. pl guide me Sabikur Rahman email ID: YYYY@YYYY