Answer
Rinse and repeat with Head and Shoulders like five times or until the flakes are gone. And use it every other day since you seem to have a lot of it. This same exact thing happened to me when I was thirteen, after a really long time of using it everyday, most of it went a way. I still have dandruff but it's really, really mild. Dandruff shampoo's save your scalp but KILL you hair so be sure to use another line of shampoo and conditioner along with it. If you have oily hair remember to shampoo every day and only put conditioner on the ends of your hair. And if you have dry hair, use a shampoo meant to moisturize your hair every day along with the head and shoulders. I would recommend using Paul Mitchell shampoos and conditioners along with a Head and Shoulders shampoo. Also in the winter, dandruff is more apparent since the air is really dry and people put heaters on all the time which takes out the humidity in the air and makes your scalp dry which makes it flake. SO be sure to use conditioner every day in winter.(When people use air conditioners, they also dry out the air and in turn dry out your scalp). No one knows what exactly causes dandruff but it usually comes when your scalp is really oily or really dry. Hope that helped!