you need to figure out how he's doing it and why.
if he is bumping against rocks... well then take them out or if he rubbing against them, then you may have a parasite problem causing it. if you have other fish in the tank, make sure they aren't attacking you oscar and causing it.
fins will heal, use melafix like said above to make sure no baterial infection happens.
You need to figure out what is causing the problem, once you take care of that problem solved, just keep clean water and add some melafix and your fish will return to normal.
good luck