Here's some advice from someone who could get poison ivy by looking at it.

Go to your drugstore and buy a tube of Zanfel, about $30 a tube, but well worth it. The stuff is a gritty paste. you need to follow the instructions exactly but here's what you do. Wet the area and push out 1 1/2 inches of the paste (it has a measuring device on the package if you need it). Mix the paste with a small amout of water to thin it somewhat. Apply the paste and rub it on the infected area until the itching stops. You can then leave the paste on for a short time or rinse it immediately. You may have to do a second or third treatment. The results are incredible. I used it for the first time this year and it works great! No itching and only the rash is left. It will eventually go away, but you can sleep without the itching. The paste pulls out the urishiol out of the skin. Apply it as soon as you can, you won't regret it!