Oh boy. So, the only thing I can think of is a methyline Blue dip. I'm not sure if he will make it, but if that doesn't work and he's still eating, then add vitamins like Selcon or Vitachem to his diet and watch for red marks or "bruising". That would indicate internal injuries or infection and there's not a whole lot we can do except treat with antibiotics like Kanaplex or Furan2
Methylene Blue: Treats ammonia burn, cuts, injuries. Will
possibly detoxify a fish that has been exposed to cyanide poisoning.
How To Treat - Comes in both liquid and powder form, sometimes mixed in with another medication. So, follow the directions on the label. Generally used as a 30 minute bath/dip at double dose, but you can also dose it directly into a quarantine tank. Aerate heavily. You can combine M Blue with nitrofurazone (active ingredient found in
Furan-2) if needing to treat for a bacterial infection. In fact,
Nitrofuracin Green Powder contains both medications and is great for treating open wounds or sores.
Malachite Green is sometimes used in lieu of M Blue, but it is considered “harsher” on fish than Methylene Blue.
Pros - Highly effective.
Cons/Side Effects - Depletes oxygen from the water.
More info on Methylene Blue:
http://www.americanaquariumproducts.com/AquariumMedication3.html#methylene_blue
More info on Malachite Green:
http://www.americanaquariumproducts.com/AquariumMedication3.html#malachite_green