What Causes Pain In The Neck And Left Arm?

Hi, my name is Rudy C 29 years old. Today after leaving work on my way home, I suddenly got a sharp pain in my neck and left arm and it hasn't left. The pain is similar to a stiff neck when not sleeping properly but I never experienced it accompanied with arm pain. It bothers to turn my head to the right. At the moment I'm just using a heating pad to soothe away some of the pain. I haven't used a pain reliever because I'm on Dexilant and not sure if it would interact with the pain reliever. Any advice? It would greatly be appreciated.