Thanks and welcome to HCM..,
According to your history...,it could be VITILLIGO...,
With unknown cause..
But your child have only 3 years so ..good treatment is available.,
VITILLIGO....Organic specific auto immune disease charcterised by
Depigmented, usually symmetrical (may not be)..
due to antimelanocytic antibodies
no itching.., only burns on exposure to SUN ...ok.
good treatment is there........
but not universally successful...
1) Topical use of Clobetasol
cream...Tenovate glaxo company..,
2) De-worming the child by giving Levamisole
3) Use sunscreen lotion on patch avoid burning sensation......
4) wait some more months for result, it will take time..,ok