A young tall gentleman, with no other medical background, smoker of around 20 cigarrettes per day, and drinking alcohol around 16 unit per week, was referred by his GP to your clinic due to increasing of epigastric burning pain, with some nausea feeling for the last 2 months. There was no vomiting, no haematemesis, no reduced in appetite, no weight loss. In addtion, there was no change in bowel habbit (ie no constipation/no diarrhoea), and no malaena. There was no family history of gastric or bowel malignancy. He was given proton pump inhibtor once a day dosage by his GP around 2 months ago, but the control of his symptom was not satisfactory. All his blood tests, including full blood count, renal function, liver function, and coagualtion profile were normal. What is your working diagnosis for him ?? What will be your next step of investigation ??