Suggest Treatment For Severe Pain On The Neck And Shoulder

I've been having really bad sharp pain in my left shoulder, along with intense neck pain/aching and a feeling of burning in my neck/upper shoulders for about a week now. It is difficult to move my left arm, and the same arm feels like it's on pins and needles most of the time. I can't turn my head to look either left or right. It's far past the point of normal discomfort. It gets worse at night, and also it's too painful to lay on my back because it feels like there is sharp pressure being added to my spine along my neck. What I am wondering is when I should be concerned enough to go to the ER or Urgent Care?