Nose bleeds are uncommon complications of seizure attack, since the blood pressure rises during the attack.
Since he has nose bleeds even before the seizure, he need to be evaluated for chronic sinusitis, blood disorder, or even checked for brain vessels abnormalities and other brain lesions.
Presence of teleangiectasia (small dilated blood vessels) may result in nosebleeds and seizure.
See a pediatrician for correct diagnosis!