I have the same problem too, its like dark brown and the skin is not smooth and slightly more sensitive than other parts. But it doesn't itch or anything, so I don't think its fungus infection. I've had this discoloration for more than 7 years and it definitely affects my self-esteem as I dare not wear any revealing outfit like swim suit or bikini. Its depressing and I haven't told anyone about it. I really hope its normal.