These may be a form of hypnagogic jerks. Is she breathing normally when this happens?

I am more concerned about her right side weakness. The location of her impact suggests possible upper neck trauma. This can cause inflammation that can cause nerve dysfunction. Imaging rarely shows these subtle injuries. Using symptoms to track back to the injury is often the solution. Some times, treating the neck as if it is injured with icing, gentle traction, sleeping posture discipline, and such can lead to improvements.

Some gentle spinal manipulation by a chiro or PT or upper cervical specialist may help. No twist the head and pop the neck treatments. They are usually too aggressive.

You don't say what position may lead to the right arm falling asleep. ??

Was there a specific thing that caused her fall? tripping, etc. or could she have experienced a neurological event that caused her to fall? A transient event would not necessarily show up on a CT.