It’s critical that you immediately question any changes to your loved one that you notice. Report changes and concerns to the staff and management of the facility. All facilities are required to have a process for responding to concerns. Each city or town also has a long term care ombudsman that can provide assistance in the case of nursing home neglect. In Massachusetts, this link will provide you with some contact resources:
https://www.mass.gov/files/documents/2018/08/02/LTC%20Ombudsman%20contact%202018.pdf
You may also file a complaint with the Department of Public Health.