I drank 2 alcoholic beverages last night and today i am experiencing pain on the left side of my lower back why is this?

Hard to say: In this case you would need an in-person discussion & exam with your physician, to discover possible causes of your pain. Did you maybe get intoxicated and fall down? Injure yourself another way? See your doctor very soon.

Kidney stone: Sounds like a kidney stone; while there isn't a direct causal link between alcohol and kidney stones, there has been an association observed; some believe that the increased urine output due to alcohol causes dehydration, which promotes kidney stone formation. Pain is usually in the flank or referred to the hip/groin area.