Seborrheic dermatitis or dandruff. Me!

I will get this type of flaky dandruff and some parts of my head is like bumby I mean some kind of yellow colour crystal type which is similar to one (when a pimple dries out when we press it a yellow color dried one comes associated with pimple) or else they could be huge pit of flakes I feel like scratching that like how we scratch our wounds when we it gets dry When I scratch my head I get flakes and flakes continues to come and its never ending process and at some seasons my dandruff will be silent but sometimes it triggers so far there is no wrong in my diet or sleep patterns apart from stress I used ketoconazole shampoo not worked I'm thinking to use selsun daily shampoo will that work or use cipla 8x shampoo Please suggest me as winter is approaching and that season is lot more worse Two different pica taken with a gap of 2 months one was taken in June second one in August Kindly suggest me thank you all