Ketoconazole 2% shampoo doesn't work : dandruff

Guys, I am tired of this dandruff from last 3-5 years, since I came to US it becomes even more. May be dry weather, not having good diet, not using shampoo daily, or genetic or I don't know for what f.. reason.

I have tried lemon + curd, ketoconazole shampoo, hair and shoulder, probably every shampoo.

One thing i noticed is whenever i cut my hair to small size and wash my head thoroughly dandruff goes away it remains just lil bit but whenever my hair grows even if I use ketoconazole everyday it doesn't help to reduce it.

Should I live my life like this only ?