25M. Having a bad dandruff problem. What to do?

My head is filled with dandruff.

My hair are dry and frizzy these days. It's always itching. There are always small white flakes coming off my scalp. Sometimes they're a little large in size too.

Should I visit a dermatologist or try some anti dandruff or anti fungal shampoo? And if yes.. please recommend some good and genuine ones.