From Longman Dictionary of Contemporary Englishrunning sorerunning soreMIa sore area on your skin that has liquid coming out of it → running
Examples from the Corpus
running sore• For Horace it might have been a short madness; in Frere it threatened to become a running sore.• In fact Meadowell is an Elastoplast name like Sizewell, invented in the 1970s to disguise what was already a running sore.• And Nat was like a running sore, crabby, miserable.• But finally, she would make of it an ulcer, a running sore that would never heal.• Such protestations ferment a running sore which breeds contempt for the authorities. 