Hello
It can be due to the bad posture which leads to tightness in the muscles connecting the thoracic spine, shoulder blade and neck .
She has to do neck stretches , cervical isometrics , scapular stability exercises and upper limb strengthening .
Next Steps
If there is radiculopathy in the arm also consult a spine specialist or a Neurophysician for thorough assessment
Health Tips
Follow ergonomic advices if working ,
Take breaks at 45 min , do gentle shoulder shrugs and rotations, keep screen at eye level , use proper chair and table to work .