The only thing I can relate with the effexor and side effects was when I forgot to take it for 2 or 3 days and I completely went bonkers. I mean, my brain would not shut up; it was like someone was just hitting the "switch" button every second on the radio. I wasn't thinking anything rational, it was just a whole bunch of noise. I don't really remember what went on that day as I just stayed in my room trying to stop myself from twitching and taking my skin off. Don't just suddenly drop off the effexor! Talk to your doctor.

(EDIT)
I just found out what "brain zaps" were from the other thread, and now I know that I've actually gone through what you have gone though. I've been on Effexor for the past few months and I had a few "brain zaps" about a week ago. I didn't know that they were from the Effexor untill just now though. I think talking to the doctor is the thing you need to do; I think I should talk to mine now, lol.