How long can Montezuma's Revenge last?

Say, if you hypothetically go to Mexico and eat a bad quesadilla and start having diarrhea and it lasts a really long time, when do you finally throw in the towel and start taking antibiotics?

Specifically if things seemed better for a while, but your stomach just seems angry and you’re still farting a lot? What if it’s been a month since the bad quesadilla was ingested?

Could it really still be “The Revenge” or is it long gone?

You know…hypothetically speaking.