Hello, welcome to HCM.
There is many causes behind 
hair fall.
 These may be from 
hormonal imbalance, hereditary, food habit, environmental, 
dandruff,
stress full life etc. 
Normally dandruff is a cause of excessive hair fall. 
So,You have to follow following instructions.
 1.Don't use oil. 
2.Every day wash your scalp with selsun shampoo.
 3.In summer wash your scalp two times in a day.
 4.Take fresh fruit and fresh vegetables
. 5.Take adequate amount of water. 
6.Avoid fast food. 
7.Use selsun shampoo on your eyebrow.
But keep it away from eyes.
So, don't worry.Take care.