Face Darkening. Loose my fairness again!

I used Melacare Cream approx 2years. When i stop using it, my face becomes very dark. Then i consult a doctor.. he suggested to use Melaglow Rich cream instead of melacare. I used that cream around 6-8months But my face became worse than before.. Then i changed my doctor.. & she suggested to use Tretin Cream after Washing Face with Dove Soap. But same thing happened.. after 3-4 months my face gone worse than before. I was so scared. Then i started Melacare using again. Within 2months my fairness Came Back. Then I consulted another doctor. He suggested to use Biluma Cream after Washing face with Ahaglow Face Wash & told me to stop using Melacare. But still I'm facing same problem when i stop using Melacare. My face becomes very dark.. Even I used Melacare & Biluma Cream 2 alternative days(2 days biluma, 1 day Melacare) but still my fairness decreasing day by day.. What Should I Do..? PLEASE HELP ME OUT OF THIS!!! I DONT WANNA LOOSE MY FAIRNESS AGAIN!!