For ringworm going on that long I would definitely go to the doctor. Griseofulvin (sp?) is an oral medication that is taken for 30 days.

As a preventative my pediatrician told me to have my kids use Selsun Blue as soap, from head to toe, twice a week during wrestling season. I also heard that if you have your wrestler use lotion every day to prevent dry cracked skin that it could also help avoid ringworm.