Atrial Fibrilation

I've posted in here before about my PVC's. I am a 34 year old male. The PVC's are actually quite under control. However, yesterday presented a new problem.

I was leaving work about 330 and forgot something, so I jogged lightly back inside to grab it. On the drive home my chest felt kind of funny, like gassy or something. I got home and checked my pulse and my heartbeat was all over the place. Hard beats, normal beats, normal rhythm, rapid rhythm. This of course, set of my anxiety a bit. Went into the doctor for an EKG and was having atrial fibrilation with heartbeat of 158. The doctor seemed a bit confused as to why this was happening. After leaving the doctor it went back to normal about 45 minutes later.

Now, ever since my diagnosis of PVC's I am very in tune with my heartbeat, etc. so I am 98% sure I've never felt this atrial fibrilation before. I am racking my brain thinking of what caused this. The only thing I can think of is I have drank more alcohol than usual the last couple weeks, during a family camping trip then i had some friends in town this weekend. Could it be some mild form of withdrawal/dehydration? I don't drink caffeine or smoke and I was not stressed out or anything yesterday.

Yeah. I'm going to get an echo. Ihad a 24 hour monitor back in May that found the PVC's and nothing else. I guess I'm just confused as to why it happened, out of nowhere for no apparent reason, in the middle of the afternoon.