Make a cup of Camomile tea and allow to cool (even put it in the fridge to make it cooler). Bathe the rash with a cold tea a couple of time a day. They say the calming effect of the Camomile can have the same effect on skin irratation as it does with the internal system. Good luck
I have several friends and neighbors who suffered similar symptoms from treatments with chemotherapeutic agents. One neighbor and her doctor decided that the Prednisone and cortisol cremes were actually causing some of her symptoms. Always feel free to ask your doctor for other options. Nurses are another great source of advice.
For relief, one neighbor used aloe on her skin, and took lukewarm baths using a product that I think is called Aveeno. It is an 'oatmeal' based skin care product. If I am thinking of the right product, that same product is also available in a lotion formula. Another friend said that oatmeal-based lotion was recommended to her by the nurses at the cancer center. I hope that you find some relief.