Alright,
1. Dose the melafix for the full 7 days (follow directions on the back of the bottle)
2. Dose 1 tablespoon of aquarium salt for every 5 U.S gallons
3. Dose the salt for 7 days, then do 2 50% water changes, wait a week, and start again if not healed.
4. You need to have the filter running, but you'll need to remove the carbon in the filter if there is any.
5. Yes I did say sand, pool filter sand works best... DO NOT use paver sand.
6. You can't fix neurological damage sadly, but you can make his environment as comfy as possible.
7. If it happens again, you'll just have to keep treating I'm afraid. It's just like owning a child with special needs, you have to sacrifice some normalities that the fish can't handle.
8. The sand should help stop it from happening again.