Have you ever scratched your head til you feel you picking your brain out. Its very common to have itchy scalp expecially when wearing extensions. These is caused by micro organism beneath your scalp they feel irritable or sensitive to the extensions seating on you scalp or therefore in that way it will cause them To be over reactive which they will produce Too much Sebum or less and that is what causes the white fatty or oily dry skin. Best way that can help is wash your hair Or apply scalp moisturizer it will help to calm and sooth the scalp. Usualy it should last few days then it goes away if it persist and you get sore or red skin or reaction its best you visit your hair dresser and take a break from extensions. During these time Avoid any chemicals styling products or products with perfume or any tension on scalp until the allergy is treated. Usage of deep hair treatment is adviced during these time.