Male Baldness Info

About a month or so ago, I realized that my hair was thinning in the front, so I went to a Dermo. He said that it was probably male pattern baldness, but that my scalp was pretty dry, so he gave me this shampoo called Ketoconazole. I’ve been using it everyday (like he said), since, and my head improved, but now the past few days it has been extremely itchy. I told my mom to look at it and she said that it looks better than before, and not irritated or anything. It’s a really bad itch that feels like its going right down the middle of my scalp, and I don’t know why. I just took a shower, too.
I’m a 17 year old male, and I’ve also been taking GNC Nourishair vitamins and eating a ton of protein. My hair’s thickness has improved, but I want to get rid of this itch!
Thanks!