A girl on my team has/had Osgood Schlatter and she stayed off of it as much as she could. If you think it's Osgood Schlatter then maybe consider getting her a brace. If you can't get a brace for some reason,tell her coach about this and the coach might be able to tell if she has it or not. Also,trying putting an ice pack on her knee and maybe that'll help. I hope she is feeling normal soon and can be out of pain.