How Can Knee, Back And Stomach Rashes With Lumps Be Treated?

my two year old has a rash which started on the back of her knee there were 7 little bumps that looked like pimples then a bout a week later there were little clusters of them on the same area. they dont look like pimples any more they are bumps the same colore as her skin. now it seems to be spreading she has some on her back and on her stomach and now on her arm and some on the other leg. she dosent have a fever and its not bothering her. im using lotramin on her to see if will work i also tried cortizone but only for a day. is it some thing i should be conserned about or could she just be having a reaction to something.