Hi one needs to rule out whether the pain is of cervical (neck) origin or of shoulder origin. She will have to undergo some special manual test with a good physio and come to a proper diagnosis. Also remember when ever healing takes place it's never a linear graph, it always has ups and downs ( sometimes the pain increases and sometimes the pain reduces). But in totality the patient get better only if the diagnosis is correct. Follow the advises given by your doctor seriously and go for your treatment sessions regularly!

Is the pain in the entire arm? Is it associated with tingling or numbness in the arm? Does she have associated neck pain. If yes get an xray done. And may be later mri.