Is there such thing as being allergic to alcohol?

So, I have never been a big drinker. However, I am also not a light weight either. But, the problem is, when I drink (and this is in all seriousness -- not a troll question or a dumb question) it really upsets my stomach. I have two go to the bathroom a lot (number 2) and it just makes my bowels not feel well. Is it possible that I may have some sort of allergy or is this normal? I mean I feel like that generally after the first drink. Any help is appreciated.