salt baths and fridge would be a good idea. Make sure the water is low enuf for the her feet to rest on the bottom of the container, and just covering her top fin (this might help her to stop her leaning on the side, and destress her).
Cover the container with a lid, and wrap in a teatowel so it stops the temp fluctuations (when the door opens) and cuts down the light when its turned on. Also, bottle of dechlorinated water in the fridge (or keep a spare container of dechlorinated water next to it - this makes for a quick transfer into another container, same temp, when doing the daily water changes ) The salt baths will help if it has an infection or fungus.
PS: won't heal overnight, may take several days or even weeks.
Also, might be an idea for him to get his water tested at the local petshop/aquarium if he doesn't have test kits. If unsure, he shud be testing for ammonia, nitrite and nitrate levels. Post figures here if unsure and someone will help.
