Neck pain for 5 months

Have had neck pain and lack of motion for the majority of the year. I believe it started when I pulled my neck muscle and it hasn't healed and now my entire neck is stiff/feels pulled or strained. But that should have healed within 1 month.. If I make any sudden movement, it feels like I pulled a muscle in my neck. GP prescribed flexeril to take for 2 weeks and to get rid of a pillow for a rolled up towel. I don't have any other symptoms(fever, arm pain, etc). When should I try to get a scan of some sort? What kind of specialist doctor do I need to go to?