Hello and hope you are fine.
Based on your symptoms it is possible that you are suffering from Tinea versicolor.It is caused by yeast called Malassezia furfur which normally live on the skin of most adults. This fungus produces a chemical, which inhibits the normal production of pigment in the skin resulting in areas of lighter skin .The other differentials of your condition are Pityriasis alba which produces mild, patchy lightening of the face, shoulders, or torso. In vitiligo there is a permanent loss of pigment. It is best to schedule an appointment with a dermatologist and get checked. Treatment will depend on the cause. I hope you find this information useful.
Best luck and regards!