Thank you for asking the query at DoctorSpring.
The back pain (the more ‘internal’ kind of pain) you have experienced after having drinks for two consecutive days could be due to 2 reasons. First and foremost possibility to be considered is an Acute Pancreatitis, or in other words an inflammation of the Pancreas. Pancreatitis usually present with more severe pain, also with upper abdominal cases. But it can also present as isolated vague backpain. Pancreas is retroperitoneal organ. That means it like near the spine. This is the cause of backpain. There could be associated nausea, vomiting and general fatigue. Bending forward can relive the pain in some cases.
Another possibility is Alcohol gastritis – an ulcer like irritation of the stomach and upper intestine. This is much more common in occurrence. Other general causes of back pain (not alcohol related) can be considered at a later stage.
In your case the most probably diagnosis would be an Alcoholic Gastritis. But the reason why I have mentioned Acute Pancreatitis is because that is the condition which requires attention. I recommend visiting your Doctor or ER as soon as possible for clinical examination. You will need to do a routine blood examination, USG abdomen and two specific blood tests – S.Amylase and S.Lipase.
DO NOT consume alcohol any further. Drink plenty of water (only if you have adequate urine output). You may take an OTC medication like Prilosec once a day in empty stomach as this can help in the Gastritis
Hope this helps
Please feel free to ask followup questions.