Anne,
Dr. Steve is currently offline so I will try to help you. I agree that it could be your gallbladder. Furthermore, the pain you have is also characteristic of pancreas problems too. Sometimes gallstones can travel down the bile duct and get stuck in the pancreas.
As far as the pain, here in the US, we prescribe narcotics for this. In the meantime, you might try over the counter anti-acids or pepto-bismol but I suspect these won't help. If you have gallstones that are passing or stuck trying to pass, you may need surgery.
If the pain is truly unbearable, or if you have a fever of 37C or higher, uncontrolled nausea and vomiting, you should report to the hospital. To see if these are gallstones or an inflammed gallbladder, you will need an ultrasound of your gallbladder.
In the meantime, no alcohol at all and avoid fatty and spicy foods. A bland liquid diet is recommended (without dairy).
See:
http://www.nlm.nih.gov/medlineplus/ency/article/000273.htm
Regards...
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