Our family just went through this. Culprit was some bad tomatoes that were left out. Put all your food away in the refrigerator, microwave, oven, etc. Put a bowl/lid on your drain, put a lid on your trash, even a piece of cardboard will do. Set out a jar with Apple cider vinegar, a piece of plastic wrap with a rubber band and small holes on the top. Be vigilant, it will take about a week to fully eradicate them.