Help with identifying my scalp condition

Hi, I’ve been trying to figure out what condition I have for half a year now. Since January, I’ve had extreme scalp itching with almost no inflammation or visible signs of irritation or flaking or rash. From February-April, my scalp was still very itchy but also my arms and legs were very itchy as well. In May, it was back to only my scalp. And now, it has moved to parts of my neck sometimes. I’ve tried “Nizoral Scalp Psoriasis shampoo” on Amazon and it’s worked well in reducing itchiness. However, it hasn’t gone away completely and still gets bad. Looking for ANY help.