Very sorry to hear that, I feel so bad for all of you.
We ate at what almost had to have been the same restaurant, by the beach, overlooking the water, 2 1/2 years ago. We also had the fajitas (at an extra charge) and I remember it as some of the best I've ever had (I like very spicy food). We didn't have any problems, aside from the ferry to the mainland, but that's an entirely different story. I bet this particular restaurant is extremely careful since it depends on the cruise lines, but anyone can have a bad day. We all did feel the effects of a post cruise dinner at Chichen Itza that year, but we should have known better in that case and were lucky it didn't affect our vacation.