Hello,
It can be due to dandruff or seborrheic dermatitis. Sometimes it can be due to fungal infection/ring worms they start out in spots of thick patches of flakes throughout the scalp then they end up uprooting the hair in the hair breaking it off until there is a bald spot. This is highly contagious and if someone in your house has it you should not be sharing pillow cases or sheets with them of the scalp. Medicated shampoos and creams are useful in such cases.
Eat a healthy diet. You can also take vit B6 and vit A and E which are good for hair and skin. Try medicated shampoos for dandruff. There are a number of over-the-counter shampoos available that can help. The most effective ingredients -- antimicrobials -- to look for are zinc pyridinethione, selenium sulfide, sulfur and ketoconazole (also available by prescription). If your hair is colored, don't use products with selenium sulfide or sulfur.
If the symptoms persist please consult a trichologist for the confirmatory diagnosis and treatment.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.