I got PI last spring in Ohio in my back yard. I had it for about 3 weeks. I got rid of it only to get it again a week later. I think it lasted for about 2-3 more weeks. I didn't do any shots but I found the best thing for the itch was applying Caldril. You can pick it up from any drug store. The first time I got PI in my adult years I went to an Urgent Care and the Dr. said get Caladril. It will dry out the PI and help the itching at the same time. I have found that the more one keeps the PI moist the longer it stays. If you dry it out it will scab over and start the healing process.
Unfortunitely I have it again but this time I'm pregnant. And it is VERY close to one of my eyes. I usually don't like taking drugs for this unless I have to. I called my Dr. & he is perscribing some pills to take that are safe while pregnant. So if you have PI close to your eyes, call your Dr.