Better safe than sorry - go see a doctor!
I had a skin infection on my shin that I thought was some poison ivy! Next time I will be careful picking at something on my shin that I was wondering if it was a tick or not after handling a bunch of freshwater fish! Darn ointment was about almost $45.
Be careful because the oils from the PI could still be on your clothes you had on. If you have a dog or cat that goes outside - those furry beasts can give you PI, too.
If it is PI -> Prednisone dose pack is the quickest way to clear it up. I had to take it about 3-4 times me life so far.