This is a tough one ....
The floating upside-down seems to be a swimbladder dysfunction, except there are many different causes of that, and it is difficult to figure out what is wrong.
The simplest cause of swimbladder dysfunction would be constipation or gas in the gut. The fish is out of balance because of the air in the belly. Feeding peas is the first line of defense. Even if the cause is not gut problem, feeding peas is not harmful.
Now, if you are sure that it is constipation (say long dark stringy poop that is stuck to the fish's behind for a while), and peas don't help, then epsom salt is worth a try.
However, if the poop is white & thin, then it can be bad. If you have been feeding white food, and the poop is white & thick, that is Ok. If the "poop" looks like a string of sausages, with little bumps at interval, that is an egg sac. Females that have no mate will expel the eggs like that. that is also normal. However, if the poop is white & thin, that is more than likely an intestine infection. If the fish is also appearing sick (lethargy, balance problem, not eating), then it is worthwhile treating.
Since the fish did have a balance problem, and some swimbladder dysfunction may be caused by an internal infection, couple that with the thin white poop, it is worth a trial of antibiotics. <It is possible that the wounds from the falling scales got secondarily infected.>
The best way to treat this is with antibiotic food. Something with Kanamycin is the current best. Look for Medi-Gold or Medi-Koi. But pretty much any antibiotic food with Kanamycin is useful. If you cannot find that, a board spectrum antibiotic is 2nd choice - eg being sulfa (ie Jungle's anti-bacterial food). Tetracycling may be helpful, but the old standby - erythromycin is no longer effective due to development of bacterial resistance.
If the fish will not eat, then kanamycin in the water is your best choice. Other antibiotics are not well absorbed when used in the water. However, using anti-biotics in the water will risk killing your biofilter, and you will have to manage a possible cycle on top of all the other troubles.
In addition to antibiotic food, other adjuncts to use are:
1. Maintain clean water - this is a must - no amount of med will work without clean water.
2. Increase temperature (to mid or high 70's) - you will need to maintain good aeration as well. Higher temp increases the metabolic rate of the fish & increase immunity, helping the fish to fight off diseases.
3. Maintain good nutrition - feeding the fish good quality food, some think that garlic may help immunity as well.
Keep us posted on the fish's progress. We are all rooting for him/her.