Re: PLEASE comment, i need some advice :(
You didn't say what kind of meds you are taking (antibiotics, steroids, ?). It seems really strange to me that they would give you an iv for a skin infection that they're not even sure you have. Normally I think you would only get iv antibiotics for really bad (and confirmed) cellulitis.
Scratching and breaking the blisters is what causes scarring; if you can leave them alone it's unlikely you'll have any permanent scars.
The confusion about whether it spreads may depend on what you mean by the word infection. The initial rash from poison ivy is not an infection; it is an allergic response. There are no viruses or bacteria involved, just a substance (urushiol) that your body really doesn't like. The rash only happens once the cells in your skin have absorbed the urushiol from the poison ivy/oak plant. Once it is absorbed there is nothing to spread. This is what people mean when they say poison ivy doesn't spread.
It is possible that your doctor was referring to the secondary skin infection rather than the allergic response. The vast majority of skin infections are from staph or strep bacteria, and they are indeed very contagious. The lymph (yellow clear stuff) oozing from the rash carries some of the bacteria with it, which spread infection. You should make sure to keep the rash covered loosely with gauze or bandages, use whatever antibiotic you were prescribed until it is all gone, and wash your hands a lot, like at least every hour you're awake. Don't share hand towels, razors, sheets, or clothes with anyone until you're done with the antibiotics.
Best of luck in getting over it fast. I'm typing this at 2:30 in the morning because I'm still itchy from an exposure three weeks ago. :(