My mom has been having some pain. How many sessions is necessary?

For the past 3 days my mom has been having some pain in her shoulder and she even feels it in her jaw when shes eating. Shes overall in good health and hasnt had any problems except she broke her arm in a car accident a few years back. In the morning the pain in her shoulder was pretty bad and she she had a headache and some blurry vision so she went to the chiro and he took an XRAY of her shoulder and hes recommending her come back once a week for 15 weeks. Does that sound like too many sessions or does that sound about right?