My Mother Hit Her Head On The Driver Side Window

My mother hit her head on the driver side window in an mva yesterday. Despite me instructing her to go to the ER she didn't go. She c/o headache, feeling tired & weak yesterday. She denies feeling any of those symptoms today with exception of tenderness at the site when she touches it. She wants to wait until Monday to see her PCP. I recommended she call the PCP on-call, but she said that her office doesn't offer that. I do not live near her, so I'm unable to assess her. What should I instruct her to do?