"Randomly" ... well, no. You had the disease for 3 days before it turned you into a Vamp. Lots of time to get it removed before it turned you.
Restore to an earlier Save file.... you do make back-up Saves every once and awhile, right? Of course you do.... it's common sense.
Otherwise, you have to http://www.uesp.net/wiki/Oblivion:Vampire_Cure