Well, the chemical attack seems to be over. :/
I really doubt it was the food. It's just plain ol' Pedigree, but she usually consumes mass quantities of it without any problems. These ass-gas attacks are fortunately rare.
I'd bet she found something disgustingly tasty while she was out playing in the yard yesterday. No matter how much I watch her, she'll find a pile of rabbit turds or something equally nasty and chow down like there's no tomorrow.
Charby, mine has the iron-gut too. She has a penchant for paper towels, and certain other delicacies... like this: