Hello and welcome to e health forum.
Since the X ray of the chest as well as the EKG is normal, conditions that can be worrying like pneumonia, bony lesions, and cardiac conditions have all been ruled out.
Hence there is no need to be anxious about them.
The other causes of pain could be musculoskeletal pain or due to acid reflux related pain.
Hence treatment with pain killers like Crocin or Ibuprofen syrup, as adviced by your doctor will help in musculoskeletal pain. You can also give her Gelusil MPS syrup, which is available over the counter, for acid reflux related pain.
In case, that is not helpful, you can consult with your doctor to rule out any rheumatological conditions.
I hope this helps.