The plant oil is the issue. Popping the blisters does not spread the poison ivy. Wash everything that you were wearing or you could spread it again when you wear the items again.
As far as the itching goes, you need the blisters to pop and dry out - for this go to the beach. Get in the water and scratch (it feels so good to scratch), get out in the sun and let it dry up. Do this 2-3 times and you should recognize some relief within a day or two.
Nothing scientific about this, but I have found that this relieves the itching pretty quickly - for me.
I am in the middle of my two week PI drill. Two days after exposure it shows up as a mild irritation. Progressively gets worse for 10 days then dries up and gone about day 14 or 15 after exposure. Bleach, salt water, oatmeal, kerosene, gasoline, listerol, prescription hydrocortisone (injected, pills or lotion), ice packs and various internet suggested snake oils all ease the itch for ten minutes or so. For me its a two week pia. I am 50 plus and get it twice a year like property taxes.
regardless of what you read, jewel weed works, I've saw too many results from people who I introduced to it, one even preferred jewelweed to cortisone shots, usually starts to dry up on day 3. you may know jewel weed as wild snapdragon, grows next to creek beds and gets orange flowers on it.
Bleach, I take a rag with bleach on it in a zip lock. Use it if I get in it, then take a bath with a couple cups of bleach in it. Take the bath even if I don't think I got in it. This has stopped me from catching it.
the main thing is learn to recognize it, poison ivy, poison oak and poison sumac, if you abide by the info in the vid I posted you won't get it bad like some do, another tip....never ever burn it, if it gets in your lungs from breathing the smoke you will suffer problems for years possibly.