I periodically experience a crawling sensation on my head that feels like bugs are crawling around. It always starts at my front hairline just to the right of my widows peak and travels back. I have checked my hair for a spider or bug and have brushed my hair briskly but I can't find anything. I remember my mother making comments when I was younger about feeling like her scalp was crawling. She died of a heart attack. She was my adopted mother so there is no generational disease of heart attacks that are passed down to my generation because we don't have the same blood line or DNA.
What causes this?

Thanks