You might also look up trigger points - there are websites with interactive body maps , symptoms and can help to find out if you have them.
If you have trigger points- stretching will not get rid of them, you have to apply pressure right on the tender spot until it fades away..then gentle stretch to bring good flow into the area..
The wrong stretches or too aggressive stretching can make things worse..

This is a good one for neck & upper back..
Pain Reference Chart
you don't need any special tool, a thumb or pencil or such works fine..

trigger points chart - Google Search