Are there hidden spices causing stomach bugs in curries.

The most frequent hidden culprit is actually freshly squeezed coconut milk that has been left sitting out in the ambient tropical heat for too long. It ferments and spoils incredibly rapidly breeding severe bacteria.

If you are eating at a small local buffet late in the afternoon the food has likely been sitting unheated for hours. You must strictly eat at busy places during peak lunch hours around 1 PM when the massive pots of curry are boiling hot and entirely fresh.