Pain and bruise
usually occur due to trauma, ask your daughter sincerely and to let her recall if there was an accident or trauma in this area hours or even days before.
Children of this age might not tell evrything for fear of bring reprimanded. If there is really none, the level of pain and motion limitation is your only way to judge the necessity to seek immediate care.
If she can still walk and wear her shoes then it might just be something that can wait until your appointment. If the pain is becoming more severe, then it is a sign that we are dealing with a possible fracture
and it needs immediate care.