My 15 Year Old Has Been Experiencing Brain Fog, Dizziness,

My 15 year old has been experiencing brain fog, dizziness, feeling like she is going to pass out, and numbness on and off for the past few weeks. She feels better then the symptoms return. Periods are normal, not taking any medication. I am thinking she may have been concussed during cheerleading several months ago; however, the cheer coach did not give her a concussion test.