Hello dear, I can understand your concern, It can be either vitiligo or lichen sclerosus et atrophicus,(LSA) both are not sexually transmitted disease Both can be long lasting, in vitiligo there are no symptoms, no itching burning or hardening of skin, while in LSA there is usually itching/burning and slight sclerosed (hard) skin may be noticed, my advice is consult a dermatologist and checked it out, and if needed biopsy can be done to confirm the diagnosis, in treatment steroid cream, tacrolimus cream will be helpful in both the condition , do get prescribed by doctor before buying them, thank you