It's really hard to say why your kitty threw up, Shannonrenee. It could be so many things, including the food or something else he ate.
I'd never heard of this particular food before you started talking about it, so I googled it. I found the website, but there's no real ingredient list or nutrient analysis for any of the products. However, the site does say the food includes grains, veggies and garlic, none of which is really good for cats. I've read many times that garlic may even be toxic at some level.
Whether the food is why your kitty isn't feeling well or not, from what I see on that site, I think it's a good thing you're not feeding it anymore.
My cats almost never refuse to eat their food, and it always worries me when they do. Missing a meal or two isn't bad, but a day or two, I think, is. Only you can decide if / when Leo needs to see the vet, but I'd think about it if you can't get him to eat anything by tomorrow morning.
I sure hope he's feeling better and eating ASAP!