I feel for you! I usually have to use the prescription steriod cream to get rid of it.The benadryl brand gell works well to stop the itching and inflamation. Salt water (ocean water) and chlorinated pool water seem to help with drying it out.
Sadly by the time my body reacts to it it is about 3-4 days after I have come in contact with it, then I get the lumps, and the huge patches and the weeping, and usually I have to bandage the area with wraps to contain the weeping. I have even gotten it from a dog that was rolling in it and transferred the oils onto me!
A few things I have found that help.....
If I know I have come in contact with it , I have found that Fells Napta and Fast Orange bar soap (the fast orange is like go-jo for auto mechanics, it breaks down the oils and grease that covers mechanics hands when working with machines) I actually think the fast orange works best.
I was weed whacking a few weeks back, had it flung all over my face neck and hands, but I used the fast orange, lathered, rinsed and repeated several times, I only ended up with a few scattered bumps on one arm. If you have to work around it, doing so on a cold day when the oils in the leaves and bark are less likely to transfer as easily helps too. And of course, I cover as much of my body if I must work around it.