Don't document what she does. Tell her you cannot ethically do her documentation for her. Write down the date, time and incident and give a copy to your DNS. The next time she does this write down the date, time and incident and give a copy to the DNS. Ask to meet with her. Tell her you feel you are 1.) Being singled out and treated differently than the other Nurses 2.) being harassed on the job and that it is creating you a hostile work environment and you want it stopped. If it happens again or you are being treated differently then the next move would be to go to the Administrator and ask for a meeting. Present him/her with copies that you gave the DNS & with the dates. Tell him/her you feel like this is a hostile work environment for you and you want it to stop.
At this point......it will.
If it doesn't you have a legal case for hostile work environment.
Of course, I would say if you haven't been there long...start looking for another job. I have been in nursing homes across the states for34 years. They are not all like this. Go to Nursing Home Compare and find a 4 or 5 star facility in your area and go apply.