Go to a doctor, or an ortho, or a chiropractor or an Accupuncturist, or a deep tissue massage therapist....or better yet, all of them. Get an xray or whatever....FIX THE PROBLEM. Do one of the substitutes these guys suggested in the meantime. But dont just dismiss squats and try to work around them. I can do squats with the bar alone, it hurts my neck and traps. So I'm a pussy and use the bar pad. So what, I dont fucking care... Better than having a sore neck for a week.