Why The White Patch Of My Arm Is Recovering Slowly?

sir,age 36 years,weigt 64kg, i have a white patch on my hand . i took ayuarvedic medicine and it improves 80% but when i stopped this medicine this again spread now i have taken allopathy medicine he is suggested me to take octomop because i have allergy on melanocly.now it improves very slowly what can i do