Oily skin is prone to dandruff Apply coal tar based shampoo regularly

Hello! Dandruff is more stubborn in teenagers due to the hormonal factors. Try to keep scalp clear and keep it covered with cap while travelling. Avoid frequent changing of shampoos and avoid fruity flavoured ones. You can also go through my health feed on practo on Understanding Dandruff. You need to continue the treatment till it clears off and then use antidandruff shampoo at least once a  week so it doesnt come back. Oiliness of scalp is not an issue as long as scalp is kept clean. Hope this helps. If there are further questions and pictures then send on private chat.