Sorry about your losses. I had the same issue in my 75 gallon tank recently. My discus and corydoras looked the same as in your pictures. In my tank were: discus; clown loaches; cardinal tetras; corydoras; and rams horn snails. To treat the problem, I used Mardel Maracyn Bacterial Medication Powder as directed for 5 days. The fish looked better within 24 hours of the first dose. It was not visible on any of the fish after the third dose. None of the fish died. I ordered the medicine from the coop and as usual the medicine arrived quickly. Good luck and hope the above was helpful.
