Poison Ivy DOES TOO spread after the oil is gone!?

I am annoyed with all that I read about poison ivy. I have my yearly breakout of the dreaded rash right now. I just don't believe it when all of the sites and doctors say that after the initial oil is gone, you can't spread it more. Days, even weeks after my initial rash began, it is still working its way across my body. I have obviously showered, many times, and even rubbed my skin with alcohol once to make sure the oils were off. Just wanted to see if anyone out there has a good explanation for how this stuff magically spreads like wildfire so long after the initial contact. I have heard of the body's delayed reaction, but, even weeks later? I don't know about that.