Last Sunday I Had Pain Going Down My Left Neck

Last Sunday I had pain going down my left neck and into my arm. I went to ER and they did an EKG and said they thought I had a pinched nerve. I have had pinched nerves before and know that was not what was going on. Every day since I am getting shorter and shorter of breathe when I try to do simple task. Today I ended up with a major headache along with shortness of breathe and been in bed most of the day. Should I go to ER again?