Does anyone have any experience with Cardiac arrhythmia?

i have had an irregular heart beat for about a week now. it comes and goes. the worst time seems to be in the late afternoon and evenings. and its still there when i wake up in the morning but seems to go away after i've been up for an hour or so (but comes back later). i haven't been to the doctor yet but am planning to go. would appreciate anything you can tell me. i'm a 53 year old male, slender, work out 3 times a week. no history of heart disease in my family. i take lipitor and nexium. my cholesterol is checked every 3 months and is around 150. thanx