Okay, if it wasn't the rice cakes, then I will have to take out my IBS detective's notebook...
Here are some questions for you:
1. Did you eat anything different than you normally eat? If so, what was it?
2. What did you eat the day before? I used to get attacks when I ate an "IBS no-no" the day before or even two days before.
3. Was the food you ate organic? I have gotten an IBS attack just from eating conventional chicken. Following Heather's diet is no guarantee you'll be okay if you aren't eating organic.
4. This is not a question, but a fact: IBS attacks can be triggered by not eating on time or eating too much at one time. Small amounts every few hours is best if you have IBS.