welcome to "healthcare magic forum "
is an fungal infection
and need to be treated internally than externally.homoeopathic medicines will help to treat the cause rather than any external factor ,if overlooked it may spread further, consult a homoeopath who will be able to help you to get rid of the dandruff .
, use to lukewarm water for head bath , clean the scalp
properly with a clean towel ,do not use that towel for rest of ur body and face .
any anti dff shampoo will help you out for couple of days so for good results start medications as soon as you can .
takecare,wish you good health always !