Def. poison oak. I'm unfortunately an expert on the subject. I would get it so bad when I was little that I had to miss a week of school every couple of years. One particular time I remember it covered my face so bad that my eye swelled shut and I looked like the elephant man. Wish I had pics.
Put the affected area under running hot water-as hot as you can stand, then let it dry and cover with calamine lotion. Take benadryl and get a shot (cortisone?) from the Dr.
As far as how you got it, I swear I could pick it up in the wind I was so sensitive. Another culprit for me has been the dog. Dog ran through the stuff, I petted him, and for the next 2 weeks suffered through a swollen hand with blisters in between my fingers. Yuck!