My mom has had a rash for about a month now she is in a care home the doctor said at first that it was a infection but it didn't clear up. The doctor came again and this time said it was dermatius and given her antebotic cream but they don't seem to be clearing up she is trying to scratch she had a strock nearly three years ago and was left paralysed so she can not scratch with her hand they seem to be driving her mad
You might ask if anyone has yet taken a swab of the rash and had it analyzed to determine more about the rash.
Other irritating things are synthetic fabrics. If she's not wearing natural clothes (pure cottons and flannels) you might try switching to them, especially for her underwear.
The other thing that helped my itchy mother was silk underwear - you can get silk jersey at a reasonable price, and silk being hypoallergenic it doesn't irritate the skin and cause contact dermatitis so readily. The trouble with post-stroke weakness, as you know, is that the person is left less mobile, and the skin gets sweaty and sore where anything is constantly against it. But since this is a recent problem then there must be a new factor - hope you manage to track it down successfully.