This is definitely not ick and using a medication for ick will only further hurt/stress the fish.
What you have is a fungal infection. It is caused by a either an injury becoming infected or because of dirty tank conditions. Given where your nitrates are I would put more of the blame on the tank conditions. I suspect that you have a lot of nasties in the substrate/gravel. Because Corys spend all their time on the bottom, they occasionally show these sorts of infections if the substrate is not properly cleaned.
Given that this thread is 10 days old, I suspect that the fish in question is either recovering or has passed, but should your other Corys show the same condition, do not treat it as ick as it is a fungal infection.
If you want a medication to help, focus on fungicides. However, without fixing the cause of the fungal infection, which I suspect is dirty substrate, you will not be able to cure the fish. The dirty substrate may be caused by the tank being overstocked, which may be the case if you have 2 SAE in a 10 gallon (depending on their age).
Adding MTS (if not already present) may help keep the substrate cleaner moving forward and removing fish to other tanks will significantly assist you in both the Nitrate and dirty substrate categories. As stated previously, floating plants or hornwort will assist in reducing the nitrates, but that may not entirely solve the problem if organic waste in the substrate is the cause.