Hi,
For how long have you been experiencing this scalp itchiness?
Is there any scaling or flaking noted with the itchiness?
Several factors may be considered here. Seborrheic dermatitis, contact dermatitis and an allergic reaction may be considered.I suggest that you refrain from using the supplement if this has been associated with the onset of the symptoms. An evaluation by a dermatologist will be able to help. Seborrheic dermatitis and fungal infections may require medicated shampoos. Frequent shampooing may be necessary in your case.
Do keep us posted regarding physician's advise.
If you have yellow crusty flaking you might have seborrheic dermatitis. I suggest Nizoral shampoo or psoriasin from shopinprivate.com