The pain could originate from anywhere. It seems that the pain may be caused by the lumbar muscles (muscles of the lower back). You can request an abdominal ultrasound and an x-ray image of the lumbar vertebral column in order to have a diagnosis and begin treatment. If you feel that you are drinking too much, you might try to stop. If you are unable to stop drinking for an extended period of time, you can seek help from any number of alcohol treatment centers, mental health professionals, or support groups (like Alcoholics Anonymous). Chemical addiction (whether it be to alcohol, stimulants, depressants, etc.) is a medical condition and is treated as such.