Ok, here’s the deal.
Lots of viruses cause rashes and sore throats, not all rashes are pathognomonic of a particular virus.
So the health centre presumably outruled:
Measles (unlikely with MMR, rash preceded by 2 or 3 days of runny nose, rash starts behind ears and moves down body)
Rubella (unlikely if MMR vaccine, not usually associated with systemic illness and high fever)
Scarlet fever (which is caused by a bacterium, and would cause a “sandpaper” like rash and pus on her tonsils)
Chickenpox (characteristic rash, it looks like little blisters)
Bacterial meningitis (she’d be much sicker and have some signs of raised intracranial pressure).
The diagnosis is “a viral upper respiratory tract infection with exanthem”. Unless they want to do complicated tests for viral DNA, they won’t find which one it was.
Since all viruses (except Herpes viruses and HIV) are treated with rest, fluids, anti-pyretics and analgaesia, there is no reason to diagnose the exact virus responsible, as it wouldn’t affect management. Those DNA tests are expensive, time consuming, and in this case pointless.
If the rash looks like tiny bruises and doesn’t blanch when a glass tumbler is rolled over it, it’s a purpuric rash and is suggestive of meningitis or Henoch-Schonlein Purpura (a kind of vasculitis…it’s very rare). If it’s not, it’s just an ordinary viral maculopapular rash.
The only thing I would say is that this could be Epstein-Barr (infectious mononucleosis, “mono”), in which case they should have taken blood for a test to look for abnormal white cells or antibodies to EBV. EBV can have some nasty complications, such as absesses of the tonsils and hepatitis, so she should return to the clinic if her symptoms get worse, or she gets some new symtpoms that don’t fit with the idea of a bad cold. Amoxicillin (a type of antibiotic) can cause a drug-induced rash in people with EBV, so if she has taken an antibiotic in the last couple of days that could be the cause of the rash.
Just give her Tylenol (or generic acetominophen) every 4 hours, keep her cool, make sure she’s drinking lots of fluids and try to get her to eat something (chicken soup, toast, icecream, whatever she feels like).