How Concerned Should I Be About An Irregular Heartbeat? It

How concerned should I be about an irregular heartbeat? It has been going on for about a week. It is skipping beats erratically. I have been very tired. When it starts beating erratically it makes me feel very anxious. I don't have any sharp pains but my upper back hurts, but it does off and on almost all the time. I have made an appt. with my Doctor for this week. Today I am feeling concerned about waiting.