I have a question about sprite?

I just drank one of those mini bottles of sprite and now I have a stomach ache. It's not like a burpy bubbly feeling but like I have an empty stomach and I feel like I'm gonna puke. I didn't chug it or anything but now that I think of it every time I drink sprite I feel this way. But when I drink 7up i don't get it. I'm not allergic to anything that I know of.... Soooo what could be going on??