Good Morning Doctor. My 15-year-old Nephew Had Issues: 1. Constant

Good morning Doctor. My 15-year-old nephew had issues:
1. constant headache.
2. a couple of instances where he has feelings of blackening out while straightening up after bending over.
3. He has fallen down without his knowledge from an upright position.
He was taken to a neurologist in Chennai. They had EEG, 24-hr holter monitor, MRI. He has now been prescribed with Frisium.

Is frisium a right medication to give to a 15-year old, that too for sustained period (which is what the physician mentioned.. 2 to 3 years).
I am concerned about using frisium as I see that it has a lot of sideeffects.

Are there any other tests that need to be done for his condition to help with appropriate diagnosis? I have attached his reports, after removing his ID.