Is it normal to get a bad stomach ache every time you drink?

I go out a few times a week and I'd say atleast once a week I get a really bad stomach ache by the end of the night. I always make sure I eat something and drink some water before I go out. I can get the pain before I'm really intoxicated. I almost always drink a double captain and coke. The pain feels like a burning in the upper part of my stomach, sometimes if I throw up it goes away or if I eat something it goes away. Does this happen to anyone else? Is it maybe the sugar in the drink I order? Its really annoying and painful so I'd like to be able to figure out what's causing it.