Hi,
There are different types of skin rashes, yours look like a fungal infection called ringworm. Do they itch or hurt? In all these years, you have not seen a dermatologist? It is always better in such cases to get it checked by a doctor, as some sensitive skin areas like in your case can get affected by self treatment.
Here is a slide show from Medhelp on various skin diseases :
http://www.medhelp.org/dermatology/slideshows/Common-Skin-Diseases-and-Conditions/261
You can also post this question in the ' Dermatology Community ' for better response. Please consult a dermatologist for a proper diagnosis and treatment.
Solace