What I see is a number of scales that were probably removed in the fight with the skimmer and they show no signs of infection, but the area near the bottom appears to be older and infected. I would treat anesthetize and treat topically with iodine or peroxide and then thoroughly dry the area and rub on some triple antibiotic ointment, and then order some Tricide Neo for future treatments. Of course we like to see the numbers for ammonia, nitrite, nitrate, pH, KH and temperature to see if there is any suggestions we can make to improve the water quality as it is very important for the water to be pristine during healing.
Zone 7 A/B
Keep your words sweet. You never know when you may have to eat them.
Richard