I would suggest not dosing her with anything. If you can stop the
hassling she will heal within a couple of days.

So on to the real problem - putting a stop to the hassling. You didn't
mention how large the aquarium she is currently in is. If it is large
enough to support a couple more fish I would suggest buying two or
three more rosy barbs - that will spread the aggression around to
multiple fish and you should notice her heal up very fast when she
isn't constantly the center of attention. A group of five barbs will
also be much more interesting than two - in a larger group you'll see
much more natural activity.

Separating them is a good temporary fix but then you have the problem
of two tanks with a single barb in them. One barb by itself makes for a
pretty boring tank. Of course if your fry are successfull then they
won't be alone for long so that may be ok.

Still, I would stay away from medication unless you think it is
absolutely necessary. Others may disagree but I've never had a fish
that wouldn't heal on its own when put in a proper environment - and
that even includes a jack dempsey that was nearly beat to death by a
pack of severums. If your fish can still swim then it can still heal
itself.

-Daniel