thanks for using health care magic.
Skin discoloration can be cause by several conditions.
Common conditions but with benign prognsis include vitiligo
Vitiligo is thought to be autoimune while Pityriasis is cause
by a fungus. However, only a detailed examination would
give a better diagnosis.
So i will advise you meet a dermatologist
for a better evaluation.
Best regards and hope this helps.