I have pain in my neck going down the back of right arm. also my pointer finger feels numb, like when u get lidocaine for tooth ache.what causes this?

Nerve impingement: can be caused by being sandwiched between two spinal bones, pressed by a bulging. It can cause muscle spasm and back pain, finger numbness, etc. Prevention treatment is always recommended. See interventional pain management specialist for definitive diagnosis and management.

Numbness: May be a pinched nerve. Have you seen a Neurologist? Ask your GP for a referral.