I've been in healthcare for over 25 years. So yes. I've seen it. Cheese is milk that has been "infected" with bacteria and the bacteria have processed/digested the milk and turned it into something else. The same thing can happen to sweat and other bodily secretions if the bacterial growth isn't stopped. It's not pretty, it smells TERRIBLE, and it does happen. Most commonly in the skin folds of the morbidly obese who don't bathe.