This could be as simple as a muscle knot - which I get all the time due to tension in the neck. Pea size and bigger, along the spinal column at
back of neck
as well as along the sides of
. They hurt, and burn, etc...I have gone to a physio therapist, who has worked them out. They do come back, and will do so if you have neck tension..(stress, computer work, not standing straight, etc...) I still get them, usually from sitting in the driver seat of my car for too long.