Skin Discoloration, White spots on face.

I am doing acne scarring and pigmentation treatment from last 8 months. From start of the treatment, I was using demelan cream then i use depiwhite cream as prescribed by dermatologist. After three months I used Golite Cream on full face and Go blanc night cream after completing Golite Cream. My skin looks darker after using Go blanc cream three weeks so I discontinue this cream and start to use demelan cream again on full face. After using demelan cream for approx 40 days, I m seeing skin discoloration and  white spots on my face (5-6 big white spots on certain areas).                      Could you please let me know the reason of white spots, skin discoloration.Should I discontinue any skin lightening cream?                               What should I need to do for this problem?