Hello..
well..the reason may be genetic or due to changes in weather,water food intake as in protein insufficiency,
calcium deficiency, anaemia etc... I need to examine you for that...its better you consult a dermatologist... Make sure to have protein rich diet..have good green leafy vegetables, dry fruits etc..drink plenty of water too...I understand the problem...you can even try changing the shampoo yiubse using..thank you