I am a physiotherapist .My lower lip does not look uniform in color, there is small black patch inside and also some discoloration on inner side of lip ,outer side of lip is dark(normal color).There appears a kind of demarcation line between inner and outer surface.At times it used to appear slightly whitish too. One dermatologist says it is vitiligo while the other one says it is just hypopigmentation not vitiligo.I have tried Topinate and Picon and also pigmento tabs for three months.It looked better and more reddish during treatment days.Now it appears more reddish inside but not normal.Once I stopped the treatment after three months it appears almost the same. My dermatologist does not appear to be sure of prognosis .What is my diagnosis and what & how long should i take treatment?