I have been using tretinoin 0.025% cream on cheeks for about 10 weeks for discoloration - it's looking worse. (Photos)

Continue to use the product. What is happening is the tretinoin is bringing the damage closer to the surface, so it is becoming more visible to the naked eye. Eventually, the pigment will fade as the skin exfoliates. Your damage was light to begin with, which means it was deeper in the dermal layers. Also, the hypo-pigmentation (lack of pigment) is looking more apparent in comparison to the darker pigment but unfortunately, there is nothing that can be done for hypo-pigmentation. Do not stop the product and make sure you are using SPF daily and reapplying if you are in direct sunlight. Tretinoin can make you highly sensitive to the sun. A three month cycle of "Tret" is typical to see results. Good luck!