Hi Herniated cervical discs will often cause numbness, pain shooting down the arm and fingers with some weakness because the disc gets out of its space and pinches a nerve and the area that this nerves supplies gets numb and weak, these are symptoms that would prompt a C spine surgery. Neck pain and shoulder spasms alone could be just spasms of the muscles around the C spine. however you mention that you also have some weakness but you don t say what area of the upper limb is weak. Weakness in the shoulder could be just due to a torn shoulder ligament or tendon(rotator cuff). I would suggest you get reviewed by your doctor for a thorough examination or even get a second opinion .