Help please! is an irregular heart beat always atrial fibrillation?

No,: There are many types of arrythmias, a-fib is one one them, abide a more common type. Here is a great summary from an excellent source! http://www.Nhlbi.Nih.Gov/health/health-topics/topics/arr/types.Html.

Not always: An irregular heart beat can be due to several arrhythmias. The best way to make a diagnosis is to get an monitor while you are having the irregular rhythm. A holter or an event monitor would be needed.