Hi, my daughter was stung by an insect last week she now has a rash which has spread across her leg. Our GP prescribed her erythromycin this week but she is allergic to it so has been given flucloxacillin in capsule form she has had 3 doses of it since. The rash is still spreading and the area is turning slightly blue as well. she is 8 and a half years old. any advice would be much appreciated.