I would try my best to help you.
From the history that you have provided, a few differential diagnoses can be made. The possibilities include
b) Seborrhoeic dermatitis
c) Scalp psoriasis
Whatever the cause may be your skin seems to be inflamed which is triggering itch followed by scratching.
You should consult your dermatologist
and he may prescribe you anti-histaminic tablets to control itching. If you have scratched severely you may need an antibiotic for 5-7 days. An antibiotic shampoo, steroid
shampoo, steroid and antibiotic lotions would also help. Keep your skin hydrated, avoid direct exposure to heaters, don't use piping hot water for bath, include fresh fruits and vegetables in your diet, drink 6-8 glasses of water daily.
Do not use steroid lotions and shampoos for more than 3 weeks at a stretch.
Hope this advice helps you out of your problem.