Hello there, I sometimes get a sharp pain near the rear of my neck/head, from what I have read, the muscle is called the splenius capitis I have experienced it from sitting down and making a sudden movement to look at something. I have also felt it when i ve been standing up and turned to look sharply. It only happens once in a while, however, it feels like someone has a hold of a muscle near the back of my head and pulls back on it sharply if I get up and turn my head quickly.