I am certainly no expert but sounds like she is just eating too fast if she is only throwing up food. One of my cats does this and my yorkie does this with water a lot. There are these bowls, called slow feeders that help them to eat more slowly. Here is a link to one at Petsmart. I have seen them on Amazon as well. Good luck.
Martha Stewart Pets™ Slow Feeder Dog Bowls - Martha Stewart Pets - Dog - PetSmart