ER or wait until morning?

My LO was seen for her 18 month well child visit yesterday. Coincidentally, she developed a fever and rash in the morning and by the time we got to the pediatrician she has a 102 fever. The rash appeared most noticeably around her genitals, but she had a couple of red bumps on other areas of her body, which worsened over the course of the day. The fever battle was rough. Even after being given ibuprofen, her temp was around 101.5/102 all day and nigh. She woke this morning with no fever, but her rash had spread and become much worse. I called her pediatrician on the after hours line and was told that if the fever returns that we should have her checked out at the ER. My husband is concerned for our daughter, but we still have a $500 bill from the last time we brought her to the ER, and we probably didn’t really NEED to bring her in at that time. Well, the fever has returned and the rash is getting progressively worse. Waiting to hear back from her pediatrician again, but In your experiences, are rashes with a fever something that could wait one more day to for her to be seen by her pediatrician on Monday morning? Or would you bring your child in to the ER, regardless. Other symptoms are sore throat, mucus, runny/ stuffy nose... basic cold/ viral symptoms, which can cause a rash as well.