Hello Wasuup,
Just in a general sense, and without knowing more detail, I would look at Sodium Laurel/Laureth Sulphate which is a chemical used in shampoos, conditioners, cosmetics.
It is such a caustic cleanser that it corrodes the hair follicle and impairs its ability to grow. It is implicated in scalp irritation, dandruff, eczema and other scalp disorders and can be one of the reasons for the incidence of thinning hair. By switching to a shampoo that says SLS-free (some are in health shops, others mail order), can restore the natural healthy function of the hair follicle.
Organics do a nice one called Red Raspberry. Look out also to avoid propolene glycol.
Yeast overgrowth/candida can be another cause of dandruff/itchy scalp. Also, look at essential fatty acids deficiency, omega 3/6.
I did read recently that massaging sesame oil into the scalp can stop the itchiness etc., so maybe worth a try.
Hope you find your answer!
Candlelight x