Severe pain in right side of neck radiates down the shoulder to forearm. Pain in neck has eased but still severe in shoulder and arm. What could it be?

Radiculopathy. Neck pain that radiates down the arm is known as radiculopathy. Similarly, sciatica, for example, is due to pressure on one or several of the nerves exiting the lower spine, usually from disc material or bone growth. This can occur in the neck as well. In common terms...A pinched nerve.