Hello There is a dull pain in the abdomen , even after small quantity meal and sometimes radiate in the back , also feeling hot flushes , fatigue and lightheadedness. All these symptoms may be due to these possibilities , these include: 1 The first possibility is of hyper acidity or gastritis ( chronic , since pain is dull ) . Diagnosis can be confirmed by upper G I endoscopy . Try raising the head of your bed about 4 inches with block. It might also help to avoid eating or drinking for 2 hours before you lie down. To control stomach acid ( gastritis ) one should not drink alcohol or drinks with caffeine in them or eat chocolate or spicy or greasy food. Also take some antacid but if severe pain you may need drugs like pantoprazole-D once or twice in day . 2 The next possibility of such symptoms may be of pancreatitis , as it may cause upper left abdominal pain which is worse when bending over or sitting. Pancreatic enzyme like serum amylase & lipase should be measured to rule out any pancreatic cause. 3 The next possibility is of due to over eating ( however , you mentioned even a small meal produces this pain ) or due to tension or anxiety . In my opinion you should consult a physician and get his opinion because physical examination , clinical history is important in such cases as you are also having fatigue and lighheadedness ( if your age is 50 years high blood pressure may develop such symptoms ). Good luck