Contrary to popular belief, ringworm is actually not caused by a worm at all. It is caused by a skin fungus called dermatophytosis. It is treated with topical anti-fungal medication such as terbinafine or miconazole. The infection is typically quite sensitive to treatment, though your treatment duration may not have been long enough. I tell my patients to use the anti-fungal medication for two weeks. If it is unsuccessful, then an oral anti-fungal medication can be tried. In your case the treatment may have been unsuccessful because you have something else other than ring worm, or it wasn't treated for long enough. Other skin rashes
such as contact dermatitis or atopic dermatitis can look like ring worm and would not respond to the topical anti-fungal medications.
I suggest that you schedule an appointment to see a dermatologist
. The reason I want you to see a specialist is that I want to make sure that you get an accurate diagnosis before you go through with any additional treatment. Things that look like ringworm but aren't may require special treatment. The dermatologist can take a close look at your rash and determine for sure what it is. Good luck.