What to do if i have a history of atrial fibrillation but this did not show up on the holter monitor. any suggestions on an actual cause?

Paroxysmal: Timing is critical. If a Holter monitor did not show any atrial fibrillation it's most likely because there was no such activity during the time you carried the monitor, considering the limits of such a test. That does not mean you did not have atrial fibrillation prior to the test or a chance to develop another self limited episode anytime in the future.