Hi there ,,i'm so sorry u are having a bad time. I have been on paxil and switched to prozac and back again. I wonder if your doctor did a slow crossover from paxil to prozac as it sounds like u might be going through paxil withrawals with those brain zaps,,i know them well from trying to direct taper from paxil once. U could have as someone already mentions,,weaned down on paxil as u titrated up on prozac,,but since u didn't,,i am sure the prozac will take over shortly and you paxil will leave your system though this can take a few wks to get it all out of your tissues etc...hang in there and hope the prozac works for u better. It is a slightly more stimulating a/d than the paxil and makes u a little more assertive and but helps with anger and rejection issues i believe. They each seem to help with certain specific symptoms it seems.
All the best to u