hi..thanks for your query
Ringworm has no relation with deworming done 3 monthly.It is a fungal infection
and needs treatment with oral /topical anti fungals.
You should visit a dermatologist
to make a correct diagnosis about the same and get treated.It might be Seborrheic Dermatitis
, which is also managed by anti fungals and topical steroids.It presents with similar white patches do to the inflammation going on since a long time in your skin.To control itching , you can take ora anti allergic tablets like Allegra or Cetrizine
Hope this is helpful..Take care!