I recently got over a cold about 2 days ago. But I was lying in bed trying to get some sleep when I sneezed. Then I got this sharp pain in the back of my head behind my right ear. It felt like my brain had just crashed into the side of my skull. I then couldn't move for a few minutes and I kept seeing thing that weren't supposed to be there, like when you see "stars". That was the first time it happened and I'm afraid it will again. What should I do?