What Causes Pain And Tightness In Back Of Head And Neck?

I m having pain in the right side of the back of my neck and and pressure, tightness in the back of my head where my head and neck start like the dip in the back of head , when I try to turn my head my neck hurts when I cough it hurts and I can just fill it without moving. It s really sore. Should I go to the ER . It s been three days