How To Get Rid Of White Scales On Scalp Causing Hair Loss?

Hi. there is a fungus sort of white scales developed on my skull from last 40-45 days. it goes off in the morning after bath but gradually re-occurs during the day time and get harder and thicker towards evening. it is also resulting in substantial hair loss. Though I have consulted a dermatologist and some medicated shampoo was advised but it is not improving. any suggestions ?