If anyone is experiencing scalp acne, please see your doctor before you try any treatments because the cause may be different than you think.
I recently developed severe scalp acne and I thought that it might be an infection of some sort. But after seeing the doctor, I found out that it's an allergic reaction. My scalp was reacting to something in my shampoo. That was the cause of my scalp acne.
I switched to a mild shampoo with few ingredients and slowly, the acne is going away. I would have never thought of allergies as the cause on my own.