Sudden hair loss. It was shocking to me!

Hi im 20 yrs old recently i hv moved from banglore to my home town . So the problem is that im getting a lot of hair fall in the recent days like i can see my head if i see in mirror this happend recently dont know whats wrng but this took place with in a month ,i know my grandfather has hair baldness even my dad but might b a chance of heridity but so soon at the age of 20 yrs im really worried about this thyrs alot of gap between my hair folicals n this is at the forehead portion an middle remaining sides are fine i feel when i put my hand into the hairs n pull wit very light power i see lot of hairs coming out and i have used hair straightner when i used to stay in banglore but i did not face much of this problem but nw when i moved here it was shocking to me