Why do I have hairfall?  

Like ageing, hairfall is also common. For some, it is faster and some it is slower, for some colour of hair changes faster and some it is late. It could be attributed to heridietary, it could be due to lack of nutrients, work environment, other biological environment like sweating etc.
As I have seen hair remains quite well till 40 and one can see the grey hair, falling hair and soon makes one baldy too in case of men.
I have seen a Zoology lady professor who has hair from head to goes and adding to that she is quite beautiful. People do take a long look at her for her beauty and lovely hair.
Some are blessed I suppose.

I have the feeling this could a genetic problem-I do think there are hair specialists could be of help to you. Watch out what you eat too some foods help to reduce hair fall

Maybe you're life style is stressful, so you often times lack blood oxygen that drained the food for the root hairs.

Try to eat mushroom, it has chemicals that adds your brain oxygen. You try our product from Gano Excel called excellium capsules. Your hair will grow back to normal.

For those who have given birth this may be a natural occurrence. That's what happens to me everytime I give birth. I think the best thing to do for your case is to check with your dermatologist. It could be fungal in nature of it could be stress related.