3weeks ago, my 2.5year old child was ill,low grade fever with productive cough & runny nose.1week after medication, the symptons still persist and doctor gave antibiotics.On 4th day of antibiotic dose, the stool was semi-fluid,just once a day. Fever and all other symptoms subsided. 3days after completed antibiotic dose, rash occured over upper chest then next day it spreads over lower abdomen, back, upper & lower extremities.Rash is more marked at lower abdomen. What will be the casue of it?