Rash docs cant identify

The very last picture I posted was taken the day it developed the other pics taken today when it got worse. Sunday night I remember scratching my kneck in my sleep that's why that area seems to be the worst but the rash covers areas all over my body including genital and buttox. I was seen by my doc Monday afternoon she prescribed me a steroid and benadryl amd told her to come back if it gets worse. It got worse today so I told her about it she said let's wait it out til Thursday to give the steriod time to work. The rash is itchy. Anyone have anything similar cause my doc is stumped.