I found this because the same symptomes like POIS started to appear with reading, but much worse. I tried therapy for reading epilepsy (antiepileptic levetirecitam) and it worked. My eeg showed theta wave occilations from temporal lobe (hippocampus), which shows temporal lobe epilepsy.
Antiepileptics do not work 100%. You need also to avoid triggers for few years. For triggers like reading or photosensitivity leviterecitam is the best, for POIS carbamazepine would be better I think....