|Joe, read my posts from last year about Prednisone and it's side effects. Just use the SEARCH feaure here. It is too late since you already started taking it, but most likely by doing so, you may get a second round of rash. Unfortunately, doctor's dole it out like candy for rashes like it is a miracle cure, and then it creates a vicious circle of problems for a lot of people who are still suffering months later. You can read a multitude of bad news prednisone stories on this site alone. All steroids are very powerful drugs not to be used without caution.
You need to have patience with P.I., some people clear up in about 10 days, but I would say it takes almost a month from first rash to final healing if you have a large outbreak. That is without steroids. You might want to ditch the steroid cream too. Other things work better for the inflammtion & itch, that are safer. Good luck :)