I get rashes from the exact same foods, such as rice flour and coconut flour. Coconut has simple (or disaccharides, cant remember) carbohydrates in a form of fructose. I’m not gonna advise against cocunot flour, but I don’t eat it due to increase in my rashes.
The rashes it self will flare up every time you eat a simple carbohydrate(lactose too), and things like rice cakes or yoghurt will result in more itching.
Try to get a scraping sample from the rash areas to determine what topical/cutane antifungal creme you can use for most effect.
However, the most effective way to treat it is to avoid the things that gives you the rash in first place.