I had the same issue when my spring broke. It was broken right near tthe base of the spring on mine so it was hard to tell until I took it out.
My car has made an annoying squeaking noise from the rear passenger side lately, so I took off the wheel real quick and noticed a shiny patch of metal on the side of my shock, right in the middle. I can't find any obvious breaks in the spring, but it definitely curved inward which is causing the rubbing. Is this still caused by a broken spring, or is it just misaligned somehow?