Hi rb2002,
It takes 2-3 hours for the pill to absorb into the body, so by the time you had an upset stomach it would have been absorbed, and thus would still be effective. Too, if this was an upset stomach without vomiting, that's no risk at all, since it's only vomiting that can potentially influence the pill.
That means you can assume you had the level of protection offered by combining the pill with withdrawal, which you can find here:
The Buddy System: Effectiveness Rates for Backing Up Your Birth Control With a Second Method. Since it sounds like you really can't risk pregnancy, can I ask why you two decided not to use a condom?
I do want to say that, since it sounds like you've had multiple symptoms like diarrhea and an upset stomach over the last few days, you may want to check in with a healthcare provider if those symptoms continue to see what's going on.