What Does White Spots On The Face Indicate?

So so about 2 and half years ago i smoked marijuana for the first time. After that day i looked in the mirror and i saw a white spot on the corner of my right eye. It was only after that day have i seen any white spots on my face and ive never smoked anything since. Through out the years ive began to get more and more all over my body. Ive went to 2 doctore and they gave me elidel cream. But after a month of applying it, i havent seen the results. They ran a blood test and sampled some of the white skin for tests as well. All they said was that i have Vitilago. P.S: i havent told them that it started when i smoked the marijuana. Should i let them know? Or would it not matter?