Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns. As per your complain the symptoms of dandruff with huge flakes and patches seems to be due to Seborrheic Dermatitis and it is commonly due to fungal infection in scalp. Other causes can be stress,side effect of certain medications, poor hygiene maintenance of scalp,very cold and dry weather.. You should start using shampoo containing Ketaconazole, coal tar, salicylic acid, zinc , selenium, sulfur.. Apply a steroid lotion over the scalp.. Wash your hairs and scalp every alternate day .. You can also massage your scalp with warm coconut oil and leave it overnight as it will help in lubrication, nourishment and prevent dryness.. In case if it still does not resolve within a month consult a Trichologist and get evaluated.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.