Accident 8 yrs. ago . i had whip lash, a crack sternum, and a numb back below my shoulder blades. now i have a burn pain level 7. what could cause?

Whiplash syndrome: It is rare to have numbness in the shoulder blade region in isolation. Therefore, you may be experiencing whiplash syndrome due to your previous accident. I would seek medical attention since the accident was severe in the past and your pain level would be classified as moderate. I would not just wait and see if this goes away.

Accident: This sounds like a post-traumatic injury to the spinal cord, would recommend a consultation with a neurologist and likely a MRI of the thoracic spine to rule out a syrinx.