I have some pretty big blisters on my inner arm, near my elbow. I've been treating them with Caladryl lotion and keeping them covered with bandages. The Caladryl helps dry them out and also has an anti-itch element to it. The bandages help with any ooze or weeping, and also will help keep out infection.
On Monday I got a shot of prednisone and am on a 16-day treatment of oral prednisone. I'm using the Caladryl on areas that are still "hot" but am now using hydrocortisone cream or Gold Bond Medicated lotion on the areas that have dried out. Both the cream and lotion have anti-itch properties.
The doctor suggested I take Benadryl at night to help keep the itch away and also because it'll help me sleep. I've also been trying the Hot Shower techniques some of the others swear by. I'm still undecided about its effectiveness though.
My husband started urging me by the end of Day 2 to see a doctor because my PI was spreading so aggressively. I didn't until Day 4 (Monday) but I'm soooo glad I did. I have a whole new respect for PI. I never dreamed a simple rash could get soooo out of hand. I was kinda embarrassed about it, but the emergency clinic doctor says they see lots of cases. Hope you've seen a doctor too! Hope this helps.