If you leave the ringworm untreated the skin where the ringworm is will become painful and irritated.
The skin might also start to blister which can lead to bacteria infections and then require antibiotics to treat.
The ringworm can also start to spread to your feet, scalp and nails and other parts of the body.
When you start to get ringworm you should always treat or get treatment for the ringworm to keep it from becoming worse.