Flaking or falling of scales from head could be due to dandruff, seborrheic dermatitis, or psoriasis. If there is diffuse flaking, it is likely to be due to dandruff or seborrheic dermatitis. If this flaking is occurring in localised areas of the scalp, then it is likely to be due to scalp psoriasis. In this case, scaly patches may be seen over the elbows, knees, shins area, lumbosacral area of the back. Nails may show pitting and there may be associated arthritis.
Sometimes, a little of flaking and itching could be due to pediculosis capitis (lice infestation of the scalp). Consult a dermatologist to find out what you have.