It's not too unusual to see untrained riders puke after a first century. Once in a while I have seen racers do that too. I have had the feeling of being sick after a hard sprint at the end of a century, and it went away after easing up. It repeated three times so I stopped sprinting. From what I understand the stomach just does not work as well if you really are working to the limit. Sounds like the stomach could just not handle all that water. Or you just went too hard.
There is a bumper sticker that says.."Pedal till you puke"...