Dandruff and acne on my scalp. And acne?

I have dandruff and acne on my scalp but no redness or itching, in my teenage my scalp turned oily and dandruff appeared.  I am not allergic to any medication or foods. If I start scratching my scalp itching appears but it stops as soon as I take my hands off my scalp. If I leave it unwashed for 2 days it becomes oily and dandruff appears l. So now I  wash my scalp for alternative days to prevent oiling. My dandruff is not dry flakes falling off but it is like oily sticky on my scalp. I also tried lemons, curd. I drink enough water, I used SELENIUM SULFIDE, KETOCONAZOLE , other anti dandruff shampoos but no improvement, it goes off for 1 day and if I leave the hair unwashed for more than a day it returns.  This applies for all medicated shampoos as well, no improvement, so can anyone help and give me a permanent solution for dandruff and acne??