I have had some terrible rashes after othe potent meds and Tea Tree Oil helped with the itch............if smells awful but at least I could sleep at night. Also avoid hot baths as that makes the itch worse. Pat yourself dry after bath or shower, don't rub yourself down with towel or you will be into the scratching mode.
I keep aloe in the frig as the cool soothing effect is good during the day.
Good luck
Kitt