Vomit color question.?

So this morning I went downstairs and had two bowls of Fruity Pebbles (I very much enjoy that cereal) and shortly after I felt very nauseous. I waited for it to subside but it would not until I finally puked about three times in a row. What bothers me is that I'm still feeling a bit nauseous. I'm also worried because the vomit was brown. I've read that brown could indicate blood and I expected to have rainbow colored vomit. I puked about ten minutes after eating, would slightly digested fruity pebbles come out brown or should it have been rainbow colored? Where the heck did the brown come from? It wasn't very dark brown but it wasn't light either. It was a standard brown color.