Hi,
It seems that you may either be having a kind of fungal infection with superimposed bacterial infection or a kind of eczema called as dyshidrotic eczema.
The best way forward it to start wearing footwear which exposes the feet as well as covers the bottom part from erosion and friction.
You may give the anti-fungal application a try, however this does not appear to be a case of Ring worm.
Keeping the area clean and hygienic goes a long way in healing the lesions.
Hope this helped