Hi Sir, This Is Raghavendra!my Face Is Much Darker Than

hi sir, this is Raghavendra!my face is much darker than my body!if i do not exposed to sun for 15 to 20 days face colour starts to become white slightly, but wen i m exposed to sun even for 2 to 3 minutes my face colour goes to earlier colour(full black)! much sensitive to sun! i have tried sun lotion of spf above 40, but no use!!