I am afraid the symptoms you experienced are not typical of an ordinary gastric pain.
In general, gastric pain, which is mostly acid related, does not come with any fever. When one experience an upper abdominal pain with fever, there is a possibility of problem originating from the gallbladder, liver or the pancreas.
This explains why the medicine which you took wasn't working as expected.
My advice is that you get yourself properly assess soonest possible by a doctor to see if there is a need for further investigations such as blood tests or scans.
Endoscopy, although minimally invasive, may be required especially if there is a suspicion of bleeding from the digestive tract. At times, specialized type of endoscopy (e.g. ERCP) may also be necessary if your problem originates from infection of the bile duct due to gallstones.
In the meantime, do record down your temperature, watch for black stools or tea-coloured urine which can help your doctor in narrowing down the source of your problem and to arrive at the correct diagnosis and treatment plan.
Dr Quan