Dear Welcome to HCM We understand your concerns I went through your details. Masturbation daily twice is surely excess. I do not know your age. After 20 thrice or four times a week is ideal. There is no adverse effect on health due to masturbation. But masturbation is energy consuming. Secondly frequent masturbation can trigger anxiety like this questions you are asking. Such questions are simply because you are anxious about the habit you are following. Engage yourself in games and other entertaining activities, career etc. The black tinge of your crotch area is quite normal and it cannot be changed. It happens because of many reasons including excess sweating and bacterial action. Keep your private parts clean by washing the area with soap twice a day and keeping it dry. If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR. Make sure that you include every minute details possible. Hope this answers your query. Available for further clarifications. Good luck. Take care.