About twice a year after drinking certain alcholic drinks i will experience severe pain in my back and my sides. the pain is just like labour pains and can last up to an hour.

This : This is very unusual. My best guess is that you may have an allergic reaction to the type of alcohol or something in the particular drink you are ingesting. My best advice would be to stop drinking the beverage that causes this reaction. On the other hand, if you are drinking while on certain prescription medications (i.e. Flagyl) you can experience symptoms as you described. Take care.

Kidneys or pancreas: Alcohol can have detrimental effects on both the kidney and the pancreas, which can present as back pain and or side pain. If it lasts more than an hour, then a MD visit with blood work, may be helpful.