Your friend MUST go back to the hospital and see her doctor. Eating breakfast does not exclude the need for lunch! - we eat again, if hungry!!
The fact that she has symptoms, is an absolute indication to see the doctor.- - more so because of the fall. Some symptoms appear only after a few hours - for example, bleeding inside. She needs examination - may be a CT scan
also. This is not to frighten you - to consult is wiser and a must rather than wait and watch..