Hi! Thanks for using this forum for medical queries!
If your daughter uses computer a lot or reads a lot then the symptoms of headache and dizziness, could be due to compression of the spinal nerves in the cervical spine region. This can also happen due to herniated disc, canal stenosis, bone disease, spondylosis, poor posture etc. A MRI of the cervical spine and nerve conduction studies may be required. Please consult a neurologist.
Even though she is very young, get her blood pressure checked. This can also cause headache with dizziness. TMJ is another possibility. If she has been out in sun a lot or drinks less of fluids then it can also be due to electrolyte imbalance or dehydration.
Benign intracranial hypertension also causes dizziness with headache and a spinal tap is confirmatory. It can be a migraine attack too. But yes, all these causes should be evaluated. Discuss with your doctor. Take care!