It's a Question of Heaving
The sickness lasts for [roll0] rounds, until your stomachs are presumably empty. Caves being irregular creatures, we're presuming that you each find some hole or crevice in which to expel your barf, and this also muffles the sound of your retching. Those of you who failed the save will be ok until you next get up close and personal with the stench, at which time you will have to roll another save. Once you succeed on a save, you're good for this bunch of trogs (tribe, extended family, whatever) for awhile, but maybe not forever.