What Causes Fluttering Sensation On The Top Of Head?

Hi, the last couple of days I get this fluttering feeling on the top back left side of my head, it doesn t hurt but I don t like the feel of it, if I put my hand on my head where the flutter is it seems to go away for a short while then it comes back. It just Comes and goes throughout the day, I m starting to worry what could it be?