Hello I Have A Spot On My Middle Back That

hello I have a spot on my middle back that used to be a scar when I was in my twenties from shingles. Fast forward I am now 60 plus suddenly same scar suddenly scar mark has become inflamed and oozes green pus and is tender to touch. finally ruptured but 1 year later now is starting process once again with same symptoms . Thank ou Dr Rynne