Bacterial invasion of gastro-intestinal tract, most likely. Also known as Montezuma’s revenge. Travelling in a foreign country, your system is not familiar with local bacteria, and therefore lack the immunity. I got very sick with that problem while traveling in Philippines.
Tse Tse flies?
I have travelled in Chile and found it relatively clean.
Chile is a modern country and the water is safe to drink.
I love Chile.
There's a quick remedy for that and it's a common antibiotic. My brother-in-law is a doctor here and he's from Honduras. Over the years the family would join he and my sister for vacations in Honduras and he would always take a supply of it. Once you started feeling any discomfort whatsoever, all you had to do was start taking the pills and it knocked it right out.........At this time I don't know what the drug was.
There's a story behind that. After he married my sister back in the early 70's, they decided to return to Honduras so that he could fulfill his country's mandatory 2 years of community service as a doctor.
Not long after, their son, who was a baby, developed an intestinal illness that lasted for weeks. Finally they sought medical attention from another doctor my BIL knew and she prescribed that particular antibiotic and it cleared him right up...........
And now you know the rest of the story..........Good day!