Talk to Dermatologist on Dandruff And Hairfall

I have severe dandruff and hairfall. A dermatologist recommended sebornil shampoo last October. I am using it for almost an year now. The problem is if I stop using it dandruff come back within two three days so I start using it again. What's the permanent solution ? Also I am using shampoo daily that is not good for hair health. Topical treatments are temporary in nature, I think oral treatment might help getting rid of it permanently.