The Zoloft, as you discovered, doesn't get rid of Paxil withdrawal, so you have no idea what's causing this -- the Paxil or the Zoloft. That's the downside of moving immediately from one med to another without completing a nice slow taper from the one first. Especially Paxil, which is known to have a strong withdrawal. If the Zoloft proves problematic, taper it down slowly; don't do this again. And as far as I know, none of these is particularly great for a baby to be born taking. The other problem is that Zoloft hopefully will work, but there's no guarantee one ssri will substitute for another. Paxil works very differently than Zoloft, they both work very differently than Prozac, etc. I hope it all goes well.
I would give the 50mg of zoloft a bit of time, paxils a really hardcore drug (well...the withdrawal symptons are) and when I went off paxil, I was awake a lot, never felt tired, just restless. i've heard some people say that paxils withdrawal symptoms persist for a long time, (maybe a few months?) so I'm not sure. I would give it a little more time for your body to adjust. if the problem still persists, then try seeing if your doctor will switch you to something else.
let us know how things go! this is a great and supportive community, you should post back often and let us know how things are going with your anxiety