|The little itchy dots sound like the start of an outbreak. The blisters you had are a dead give away.
Some people get the rash slowly and it can last for several weeks. People used to believe this was becuase scratching caused it to spread or that your body was carrying the urushiol oil internally and causing it to re-appear. These are both myths.
It's possible that you could be re-exposing yourself. If you know when and where you were initially exposed try to remember what you were wearing that day. It could be clothing, shoes, and even yard tools that still have urushiol on them. It's very important to clean everything thoroughly. There is a lot of good information on this website about cleanup, etc.
I'd see a doctor just to be sure that it is poison ivy.