Strange Illness in cory cat

[Argento13]

I have recently treated my fish with Kordons Rid Ick +. I treated for four days (once every 24 hrs with 25% water change). The last treatment was wednesday night and thursday night i did a 25% water change and started my power filter with a new cartridge. This morning (saturday) i noticed one of my albino cories is rather red looking like its sore or something and is constantly swimming back and forth. Its been doing this for 5 and 1/2 hrs now. Any ideas what this might be? I have one other albino cory and two saddleback cories and they are fine, in fact thriving. Thanks for looking and any advice is appreciated.

[ewok]

did you use full strength? cories are one of them fish i think that don't take well to full strength dosing. most bottom dwellers are like this and generally referred to as scaleless fish.

just a guess......

melafix might be a thought if it is actually like a chemical kind of burn like i suggested.......