You should really consider setting up a QT
.. it would be better to be rid of this thing once and for all than have it lingering around.
If you QT
the remaining fish and leave the main tank fallow for a couple months then you should be safe to start re-stocking.
If you leave the remaining fish in the main tank then there's a chance the problem will recur and you'll go through this all over again.
I certainly wouldn't advise any new fish purchases at the moment.