Is a re-activation of ebv common? what causes it? i've had it for about a month and a half. how to treat it?

EBV: Reactivation is not rare, but also not extraordinarily frequent. There is not an obvious means of treatment which is effective although some doctors may try a course of gancyclovir if it recurs often. This will not cure it, but may reduce the duration of a specific episode. Good luck. If you want a full assessment see an infectious diseases expert.