If you do not have other signs or symptoms present, his rules out allergic causes. Your condition could be due to
skin disorders, fungal infection,
stress or head louse.
This could be due to contact dermatitis if there is a rash present with the itch. The main causes of contact dermatitis could be a new shampoo, soap, hair dye or hair product, mainly if the product has alcohol in it.
It could also be due to seborrheic dermatitis or dandruff.