My Top Lip Is Brown And So Is The Lining

my top lip is brown and so is the lining of my bottom lip, i am 15 and try my best to maintain a healthy lifestyle and do not drink, smoke or use drugs. i have tried everything from spf lip balms, other remedies but i cant find a solution, can you tell me how i can change this, nobody in my family has this and i want to get rid of this