What Does A White Patch On Wrist Indicate?

I have developed white patch on my wrist since 12 months now; i consulted 2-3 doctors as off now; earlier this was a Sunburn but one doctor suggested me that due to irritation and me scrubbing the area the same has now become white patch (vitiligo) . He gave my an Melconyl lotion which was to be mixed with Momate and has to be applied on the affected area. I did this treatment for 30 days and i saw the pigmentation happeneing. Very recently i noticed that again the white patch is appearing ; i consulted different doctor now and he asked me to apply Placentrex gel stating this is Allergic Vitiligo. I am totally confused and unaware how can I get this cured. Please help