What in skol vodka could i be allergic to? howdo i test this?

See an allergist: All distilled spirits have some additives, preservatives and the like, and you may be allergic to some proprietary chemical in the mix. Alcohol allergy does occur, but it would not be specific to the brand of beverage. You don;t say what kind of reaction you are having, and i cannot tell you whether it is likely to be allergic in nature without knowing the specific signs and symptoms you get.