This is my arm on weed

About a month ago, I was tearing out overgrown weeds and crap in the back garden. It's a huge messy jungle out there, where I can't even see from one end of the garden to the other because the lemon balm, feverfew, foxgloves, catchfly and other crap are so tall. One of the worst spots had just giant streaming vines of this weed, and I can't find out what it's called. I've been on a bunch of web sites but haven't seen a pic or description of this thing that matches. It left me in agony. It's got these kind of... hairy, for want of a better word, leaves and stems, and about five to six lobes on it in a fan shape.

This one is kind of dessicated as I didn't think to take a pic until after I'd dumped everything in the yard waste. And as you'll see below, there's a reason I didn't want to go digging through the can after I'd piled other things on top. It grows and kind of winds around and through things, though not as bad as bindweed (false morning glory). It was literally everywhere and I'm still finding hidden bunches of it. Can anyone identify it?

This is weed:



And this is my arm on weed:



It was like being branded or something. Welts all over my arms, all the way up to my armpits because I would reach into these clumps of flowers and pull it out, and it would attach to my shirt like a leech. I'm glad I was at least wearing long pants because it hurt so much, if my legs had gotten it too, I don't know how I'd have slept for a few days. They stayed around until about five days later. It reminded me a lot of the time I fell in a nettle patch when I was little, wearing only shorts and a little top.

Before I tackle this again, I want to know what I'm up against!