Melafix and pimafix combo wont do any harm - just to be on the safe side.
Dont bother netting and Q'ing it for a cut - the stress will do more harm than good - Id suggest a water change today - then throw in the M&P combo - you wont need to treat the fish as in a full course of a week - I have found with even the worst torn fins (mainly on plecs) that three days is enough
Im sure the platy will be fine - oh and feed ye olde garlic too
On this note - i read that garlic is now being pushed at the ultimate cure for marine ich - i know were not talking about ich here - just a little note of geekiness