PACs with fainting

Hi all,
I've read many of the posts here regarding PACs and it seems that I shouldn't worry, but my situation seems a little different from most I've read.  Just over a year ago I started having spells in which I felt dizzy and had something like a daydream, and the first couple of times it happened I ended up fainting.  After that I learned to just sit or lie down and the symptoms would go away within less than a minute.  I have not fainted from it ever since, but I started writing down when it happened and it seems to be roughly monthly, though not tied closely enough to my menstrual cycle for me to feel like it has anything to do with that.  I have been on birth control pills for a long time- 12 years- wondering if changes with age could be making them a poor match for me now (I'm nearly 38).  I don't have other health concerns, in fact this is the first time I've needed a doctor for any kind of illness since my daughter was born 12 years ago.  I don't smoke, only drink alcohol occasionally, eat well, not overweight, but I know I should exercise more and I'm working on that.  My job is stressful- high school science teacher.

I saw a doctor who did an EKG, CT-scan, and I wore a halter monitor for two weeks.  The only thing that showed up was with the monitor and it showed isolated PACS, no big deal, but also one episode of several PACs in a row- that would be the one incident during this time that caused me the pre-fainting symptoms I described.  If I'm sitting down when it happens, I don't pass out and it goes away in a few seconds but of course it is scary and difficult to believe it isn't dangerous.

I will be going back in to the doctor in January but would appreciate any suggestions here as to other things we should consider and whether or not this is potentially dangerous.  She did tell me this is not usually the type of condition doctors are concerned with, but that having several in a row could be problematic.  Of course, in the office I wasn't thinking straight and regrettably I didn't ask the questions I have now.  Yesterday I had 6 episodes, 3 at work- that had never happened before- each 2-3 hours apart, and every time I just sat down with my head between my legs for a few seconds and the symptoms went away.  

Thanks for your time and input.