Ringworm is pernicious, and you don't have to be dirty or something to get it. Any pet can carry ringworm.
Tinactin or the generic equivalent usually works just fine for most ringworm cases, but some are stubborn and require a doctor's examination to determine its severity.
If a ringworm outbreak lasts more than a couple of weeks, you probably need to go to the doctor and get a stronger, prescription anti-fungal cream. Since ringworm is a fungus, it won't usually just go away without treatment, and it also spreads. So you have to treat it. It’s not going to go away, otherwise.