bloated immediately after drinking a cup of water?

Do I have a problem? A second ago my stomach was flat flat, looking like a bikini model (I was so proud) and as soon as I had a small amount of water, maybe half a cup, my stomach immediately bloated, it was almost quadrupled in size :( i know his can't be normal. I have a small stomach and usually get full pretty quick but no matter how little I eat or even if I skip food and just drink, I bloat.