Hi Nashat ! Good evening. I am Dr Shareef answering your query. Even though heart problem could also mimic as a gases or acidity in the upper abdomen (epigastric region), we can not conclude on it without related investigations and a physical examination by your treating doctor. The fever with stomach pain points more to an infective origin like a food poisoning if you had any food from outside recently. I would also advise for an ultrasound of abdomen to rule any chances of a cholecystitis/cilelithiasis for the pain and fever. Till the reports of clinical examination and investigation reports are ready, you can take some proton pump inhibitor, a probiotic, and an antispasmodic drug. Further management would depend on the results of investigations and physical examination. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. Wishing you an early recovery. Dr Shareef.