Neck pain

Just a question for anyone... when would you be concerned about neck pain? I have not had any calls or accidents recently, but last night at work I stated feeling a bit of pain in the back left part of my neck. By morning, I could barely turn my head. I can look up easily enough, but if I try to move my head any other way (side to side, looking down, tilting, etc) it just hurts to much to move. It’s only been today, so I’ve just been waiting it out for now. Have any of you had neck pain like this? When did you get checked out and what did it end up being?