I did the same as a kid and it gave me mild serotonin syndrome 1 time out of the dozen or so I had done at that time period. The question is not if it will give you it, but if you're willing to risk it. If you are willing to try it, I can't really say much to stop you from my experiences with other drug users. But if you are in an informed state of mind open to the possibilities of what can happen, it is strongly advised you do not.
Oh and by the way, the zoloft is still in your bloodstream if you haven't withdrawn yet regardless if you skipped a dose or not. So you are basically still risking it just the same as when you don't skip.