Suggest Medicine For Dark Skin Near Butt And Inner Thighs

Hello Doctor, My skin is very dark near my butt and inner thighs compared to my rest of the body. It also has lot of stretch marks. I am going to get married in a years time and therefore you understand my problem. Since i have a year in hand can you suggest any remedy which can atleast make it less darker over time. My lifestyle is not very hard and fast. I'm mostly in house whole day. I appreciate you help on this.