There can be a Transient Synovitis
of the hip especially associated with any viral illness in the body; the rash in this case. Usually nothing to worry about; will respond to paracetamol
syrup & rest in bed in a day or two. If the child develops a fever & severe pain
in the hip, take her to a paedratician or Orthopaedic Surgeon
for blood tests & an Ultrasound Scan to rule out any joint infection.