Pus has formed in the wound.
Kizu ga kanōshimashita.
wound; injury; cut; gash; bruise; scratch; scrape; scar; chip; crack; scratch; nick; flaw; defect; weakness; weak point; stain (on one's reputation); disgrace; dishonor; dishonour; (emotional) hurt; hurt feelings
indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and
suppuration; festering; coming to head