What Causes Tightness From Back Of Skull To Shoulder Blades?

For the past year and a half, I have suffered from a weird problem. It started with a strange sensation that originated from the back of my head & neck and shot upward. Additionally, I started suffering from frequent tighness in the neck and mild, dull headaches that often felt like they originated in the base of the skull/top of the neck.

The best way to desribe how I feel is that I get tighness in specific lines running from the back/base of my skull down to my shoulderblades