My 6 year old present with an itchy rash and fever. yesterday complained about a sore throat. ?

Viral infection: This sounds like a common viral infection. The sore throat was the key - since that's where the infection most likely took hold. I would show this to a doctor ASAP-so they can try to figure out 'what' is causing the infection and therefore direct treatment. Hopefully your child is updated on all their shots, as unfortunately there's a resurgence in diseases that should have gone away (ie. measles)