Hi,
It seems that you are having seborrheic 
dermatitis.( SD)...
There is no exact cause.
There may be tendency to develop SD.
But, some factors may precipitate SD.
Stress,tension,worries,psycholgical upsets,
sleeplessness,enviormental factors,yeasts on  scalp,vitamin deficiencies...etc may cause SD 
Due to 
dandruff , your hairs are falling.
Avoid worries and tension.
Take proper sleep.
Have nutritious diet.
Take antifungal tablets.
Steroids in tappering dose for short period may be helpful.
Antibiotics may be taken ,if there is bacterial infection.
Biotin containing tablets should be taken to stop hair loss.
Apply antifungal with steroid lotion on scalp.
Shampoo with 
ketoconazole lotion.
You 
consult dermatologist for perfect treatment.
I think, you might be satisfied with my answer.
Thanks.
Dr. Ilyas Patel MD