It may be from using your cell phone.
When you’re looking at your cell phone screen, most of the time you’re looking down at a 45 degree angle. If you’re using one hand to make a motion like swiping, you’re adding an additional stressor on your neck. This is the equivalent of putting an extra 50 pounds of pressure on your spine.
The muscles from your fingers are connected to the muscles of your shoulder and neck like links on a chain. The muscle that feels the pain is the weakest muscle in the chain, which is usually your neck.
To prevent this, hold your phone at eye level. If you’re sitting down, you can use pillows or someting else on your lap to support your arm while raising your phone. You can also use voice commands instead of typing or ear buds when talking so you’re holding your phone less.