Hi, is her water intake optimal? If she's not deliberately drinking lots of water there's always the possibility that the discs between the vertebrae might be dehydrated, that together with an exercise of lying across in bed with the head hanging oveer a side and then slowly lifting the head and then lowering, then turning slowly from side to side, will help bring fluids to that region.
If it's muscular tension taking magnesium or rubbing "magnesium oil" on the neck could bring almost immediate relief as mg. is needed to relax the muscles. Calcium, silica, vit. D & K and even strontium could be needed if there were bone loss in the area.
And lastly, anyone taking any medication should be taking extra Vit. C with each dosage to help detoxify these drugs.