Dandruff is a common situation more common among teenagers. It can be more problematic if you are using hair oils. So consider discontinuation of oils and using an antifungal shampoo everyday for first week and then reduce the application to twice a week for maintenance. You should keep the shampoo at-least for 5 minutes on the scalp for it to act and use lukewarm water. This should solve your problem. However if problem persists, consult a Dermatologist for proper diagnosis and treatment and to rule out any other skin condition. Hope it helps you.

Please use an antidandruff shampoo like scalp. You may need oral and topical application also.one should not shampoo daily since a little sebum which comes is protective .hair fall may get controlled once dandruff is cured. Bath with warm water not hot. Hot will dry and age the skin. Avoid processed food, sugars in any form, control coffee and dairy. Get regular sleep. Drink 8glasses of water