What Causes The Outbreak Of Rash Around The Mouth And Fever In A Child?

Hi my 2 and a half years old had a bout of fever last week followed by congestion which was treated with ala hist. The dr tested for flu since she was around a relative that had it but that was negative. 2 days later she began getting a rash around her mouth that looked like pimple/acne that slightly got worse and spread to her chin and a little on her cheeks. Dr said it was just a viral thing that we had to ride out. But this evening she had fever again and the rash spread to her bottom. I m now worried about things like measles chicken pox and hand foot mouth disease. What can/should I fo? Is there anything that can help it go away.