I need details on Fifth Disease?

My 8 yr. old came home on the 2nd with a rash over her arms and legs. It never spread anywhere else. Several Dr. visits later they still don't know what it is. They checked her for Rubella (even thought she was immunized) and Rocky Mountain Spotted fever, both which were negative. The rash itched her occasionally, but not that bad, was not raised and looked lacy to pimpely. It was gone for 3 days, and now has come back, but this time it is all over her face and chest and back. I wanted to know if anyone out there has any suggestions on what it could be. She has no fever and has not had one. Her glands are not swollen either. The only allergy she has is to Penicillen. Thanks for any help.

The medical definition is this:
Also known as erythema infectiousum, this is an acute benign infectious disease, mainly of childhood. It is characterized by fever and an erythematous rash that begins on the cheeks and later appears on the arms, thighs, buttocks, and trunk. As the rash progresses, earlier lesions fade. Sunlight aggravates the eruption, which usually lasts about 10 days. For a period the rash may reappear whenever the skin is irritated. No treatment is neccessary, and prognosis is excellent. Isolation of child is not required.

I had it as a child. It was not a major inconvenience and eventually went away on its own.

Maybe she's having allergy attacks.. try changing her diet and bathing soap.
If that doesn't help try doing a herbal detox, but talk to your doctor first.

Check out Dr Greene.com Fifth disease. I am a nursery supervisor for two year olds and sometimes we have kids with the rash, we call it slap cheek. This sounds like a normal; case, the rash can seem to come and go and look more intense when introduce to heat of persperation.