In my opinion this can be happen in two conditions if u have slept in a uncomfortable position in the night or else u are suffering from cervical spondylosis..in both the condition u can do hot fermentation with rubber bottle u will get relief in few days but in cervical spondylosis u need to get it checked and get an x ray done with few blood tests like
calciumvitamin b12vitamin duric acid... consult a physiotherapist for this condition and get ur treatment started like IFT / US / hot pack.. get well soon take care
Next Steps
Consult a physiotherapist
Health Tips
Hot fermentation is a must
Do not check ur pain
Do not lift heavy weights like bag / laptop
Do not move ur neck unnecessarily