Nystatin is a chemical antifungal. Natural ones are : garlic, oregano oil (o.o.), caprilic acid, grapefruit seed extract (GSE), coconut oil, pau d'arco, etc
My all time favorites (to take orally) are o. o., gse and pau d'arco, garlic.
A substitute for the topical nystatin is coconut oil.
As per oral supplements, it is important to rotate them. Candida will become immune to them after a while, you can avoid this by using two or three different antifungal and changing from one to the other every 4 to 5 days or so. Some people choose 4 of them and rotate, morning and evening as well as after a few days.