Actually if you're thinking about meningitis the the rash comes usually a long way into symptoms. The medics I've spoken to find it frustrating that people have fixated on that because people think they're fine because there's no rash.
Ds used to get viral rashes that didn't fade and I was told he only needed medical attention if he was clearly ill or it was spreading rapidly.
Op, if she's showing no signs of illness then a&e is overkill. I'd give a dose of piriton in case it's an allergy and check again in the morning.