I had a nasty rash from Poison Oak behind both of my knees and on my left ankle a few years ago. The rash came back about a year ago in the same places and I was baffled where I came into contact with it, but thought it might have been possible that I touched it. I now have it again (same places) and am completely convinced I did not contact any poison oak. I've been wearing new long pants and calf high socks all fall. Also this Fall I've spent very little time outside.