Sorry to hear. I'm not a doctor but the advice I'd follow (I work in H&S so often have to understand common illnesses, risk assess things and provide guidance) is to take paracetamol if she's in pain, focus on keeping the rash clean and dry to reduce the risk of infection, wear loose-fitting clothing (avoid tight tough fabrics) and make use of a cold compress or iced peas to cool things down regularly. Any bandages need to cover the wounds in full to prevent infection/cross contamination. If she has a weakened immune system she should consider talking to a pharmacist to get some anti-viral medication to speed up healing. Recovery should be expected in 4 weeks, but expect the skin to be sensitive for some time after the rash has gone. Hope this helps, a full recovery can be expected :)