In Jibberjabberheim there's a silly druid who drops you a wand of shambling mound or somesuch, which when picked up will grant Rot.
You're best off ignoring the 1 hp lost per SIX seconds (not every second) and just deal with it until you get the tenebrium handling skill, at which point you'll surely have a bloodstone you can use. Just don't waste time curing it then picking up tenebrium ore without the handling skill.
