Sorry i just came home. I got and answer from the girl who text Sakure. This was the answer. I never heard about it before. This is the answer and recommendations:
I'm thinking it could be a result of the medications. From what I've read, Tetra Parasite Guard has a few ingredients that are not fish friendly. I think someone once said diflubenzeron was even used in lawn fertilizer. If the dose was just a little off, it's possible the medications burned him. Since the poop has returned to a normal color, I would recommend leaving him in epsom salts for another week to make sure the system is clear and adding a product like API Stress Coat or Kordon Fish Protector to encourage the slime coat. That should help protect the red sore from infection. I know the Tetra meds are readily available at places like Wal-Mart but they're not the best. If possible, try to get people to use API General Cure instead.
The fish's appetite may have gone off because some medications dull the sense of smell and taste. Hopefully once he's out of the meds, he'll get his full appetite back because with internal parasites, it's always important that they eat so they can poo the parasites out.