Illness question

Approximately a year ago one of my captive bred C. o. subadult (still terrestrial) had some kind of illness which I think was related to unproper cleaning and therefore some kind of bacteria. The substrate was gravel filled with water till the surface of it to always keep the moss (dried, not living) moist. The upper half of one of the newt's leg became dark red, and obviously sensitive for touching. I managed to cure it by putting the animal into shallow water with a little piece of tebang leaf in it. I changed the water every day, later every other day. I also put some vitamin (JBL TerraVit fluid) into the water after every water change, and cork bark pieces to climb out if necessary as the procedure lasted for weeks (but it didn't used them much).

Could you please tell me what disease was it exactly?

Well, i´d think it was a sore. However this are much more common in WC animals. I think conditions ought to be very inapropriate for a CB to develop a sore. He made it, though, so congrats, it´s not easy curing these illnesses.
I´m guessing you know this and it´s certainly not it, but some C.orientalis have a patch of red in the upper arm, which is perfectly normal coloration. Thought i´d mention it just in case.

Thank you for the answer! When I saw that reddish limb, I thought it must be the same problem I had with my toad many years ago, and that was caused by unbalanced diet. However I always use some mineral supplement for dusting pinheads, so the second guess was what I mentioned in my previous post. It was clearly a deviation, not normal coloration even at first sight because the dark colour of it, the enlarged, sensitive area (the newt "jumped" forward when touching it however it doesn't do that normally) and the fact that I knew it couldn't have a spot there as I saw it almost every day (or, at least, every week as it tends to burrows itself into the moss to hide until night comes) since it hatched and that stuff wasn't there before. Even it's movement seemed unhealthy. But luckily my newt is perfectly healthy again, grew larger than its father (so I think it actually a she but I never checked it as it actually doesn't matter at the moment) and an other lesson is learned.