What Causes The Outbreak Of Itchy Rashes All Over The Body?

my 68 year old mother has recently moved into a assisted living center with 2 different medical staffs taking care of her medical needs. she has broken out in a rash that is like small bumps all around her body they are not custered like heat rash very itchy she has been treated for scabies, no improvement she has been treated for bedbugs brand new building she was the first person to occupy her apartment , same bed and no previous problems like that before moving in. the staff doctor doesn't know what it is and has been treating her with antibotics. they called me and I took her to the er last night the doctor said maybe the scabies, or bed bugs or maybe marsa so now she is in isolation back at her room with no knowing for sure what it is and what to do. the rash kinda has a sunburn look to me on the skin but not like a major burn just slight color of red and the various small bumps spaced a part not clustered