Epillepsy or panic attack. Hours before.

This friend of has been facing this serious issue for past 4-5 years and we don't know what it is. Suddenly his heart starts pounding very fast,he starts sweating and his body starts shaking;sometimes complete body,sometimes just fingers. After this,he would suddenly become unconscious and remains in that state for some time,then he would awake once,he would look here and there and then he would go back to that stage again.after some time he would wake up again,bit confused but remains completely conscious this time. Also,sometimes these periods of unconsciousness remains for more than 15 mins.and during this period,if u slap him,u pour water on him,it doesn't matter.he doesn't respond. Recently,he has been facing memory loss issues also. He has to put alot pressure on his mind to remember thing that happened previous night or 4-5 hours before.