Shoulder and neck problems?

So I was laying in bed last night and I woke up in the middle of the night. I started moving my neck around and I heard a loud crack. I went to bed, not thinking anything of it. I woke up this morning to this unbearable pain. My neck was killing me and was hard to move my head around. Its also hard for me to life my left arm all the way up. What do you think I should do?