Are Intermittent Blurred Vision, Dizziness, Headache And Muscle Pain In A Teenager Normal?

My daughter has been having headaches, blurry vision, muscle pain, and dizziness. She is 13. She has been seen by a GP, neurologist, and gastroenterologist. They have not been able to identify the cause. Mostly, she seems healthy, but she has these episodes that are very scary. She has had MRIs, EEGs, blood tests (including for food sensitivities and thyroid). Any other suggestions about what this could be or what types of diagnostic testing we might try? Very concerned.