Hi ! From your history it seems that you got a severe muscle spasm in your cervical region. A course of anti inflammatory drugs for 5-6 days along with proper physiotherapy
should relieve this. However in case it is not getting relieved, and also considering the past history of trauma, you are advised to consult a orthopaedic surgeon
, who may advise you for a X ray
of Cervical spine
if need be. Wish you an early recovery.