As other expert is offline and you have severe pain so sorry for late reply and inconvenience.
As you pain is severe and possible causes may include acute pancreatitis,Gastritis.
Further investigations that may be required include
Ultrasound of the whole abdomen.
Serum Amylase and Serum Lipase
The line of treatment may include
Antispasmodic medication like buscopan etc
Antacids like prilosec
Pancreatitis is a acute emergency and usually require hospitalisation.
It is a common diagnosis in people with a history of alcohol abuse.
Second possibility include
So if possible consult a doctor ASAP for further diagnosis and management.