The OP comes across as very calm, and someone who just wanted to alert the resort to a potential problem, which should be dealt with before a more serious health hazard arose. As uncomfortable as your companion may have been, can you imagine if it were someone with underlying health problems, or a toddler? It could have been a deadly combination.
The resort was in a position to check both the food, and the food handlers, to make sure neither was a source of contamination. Sometimes, a little pep talk to the staff "One of our guests got ill after eating here; make sure you really scrub your hands" will be all that is needed. (I assume that you are all aware that you need to use soap and water, and scrub for the amount of time it takes to sing "Happy Birthday" to be really safe?)
It is also very diffricult to absolutely track down the source, as people are exposed to germs through touching railings, door handles, etc so what may appear to be "food" poisoning is actually due to germs picked up elsewhere, but the introduction of food just triggers a physical reaction. Without a complete analysis of everything involved (and I do mean EVERYTHING) you're stuck with a more likely than not diagnosis.
My in-laws suffered a case due to contaminated water from those huge orange coolers on a golf course at a VERY exclusive club. An Epidemiologist (another in-law) could only conclude that it was the most likely source...after doing a complete history of everyone involved in the incident .(my husband was the only one who didn't get sick, and the only one who didn't drink the water) In the absence of laboratory findings, that was the best that he, an expert, could do. And, as I stated, he couldn't say definitely. The course was extremely apologetic, and even grateful, as they hadn't thought about the dangers. They instituted a policy of sterilizing them (using a final rinse of bleach water) after that.
They even gave them a free round of golf for a future visit.
But I'm not sure if they would have accepted responsibility (not would I have expected them to) without a medical evaluation.