This is quite common and it is known as Roseola Fever, which is caused by virus (herpes simplex viruses (HSV)). It normally developed after high fever. You do not need to do anything if the child doesn't feel uncomfortable. But normally it will be quite itchy and you can apply calamine lotion to soothe it. If the rashes persist for more than 3 days, please visit PD.
This is Roseola Fever rashes. I am pretty sure it is as it normally develop after a fever since your mentioned here, the fever. I know as my child experienced it before. I brought my kid to PD for this rash and PD explained the same thing. Some of my friends know about Roseola Fever too, same rashes as shown in picture.
There are different types of rashes and it's best not to listen to medical advice over the internet. Do bring her to a PD if you are feeling unsure. http://www.babycenter.com/101_visual-guide-to-childrens-rashes-and-skin-conditions_10332129.bc
please take your baby to the PD ASAP. there are various symptoms that can indicate the reason for the rashes, which your baby's PD will understand best after an examination.
thanks