I Have Had A Pain On The Left Side Of

I have had a pain on the left side of my neck for about 5 months. I thought it may be coming from my shoulder although that does not hurt. It seems to be radiating upward from that area. It comes and goes, but last night, the pain was so intense I was going to go to the er. I put biofreeze on it and that helped. Should I get checked out? I find it hard to believe its muscle as I have not done anything to cause this intense pain.