Hi If your son is suffering from ring worm or fungal infection , first thing is you need to do is confirm the diagnosis, for that you should consult a dermatologist, fungal infection/ ring worm usually appear as ring shaped lesions in flexures/ folds . These lesions are usually associated with itching.

The treatment for ringworm that is  fungal infection is simple. You have to take anti fungal tablets and creams for 4 to 6 weeks following which it resolves. Do not apply soap on that area and do not self treat with over the counter steroid creams. Mistreatment with steroid creams like panderm, fourderm, betnovate, candid b etc and self treatment with cheaper generic medicine is the most common reason for recurrent disease. Another cause of recurrence is cross infection from other infected people in the house. Kindly call me or send photos using online consult option for accurate diagnosis and treatment.  If this is fungal infection, it needs to be treated as early as possible as it will spread further on your body  and also to other people in the household.