My 3 Year Old Granddaughter Just Came From The Doctor

my 3 year old granddaughter just came from the doctor with redness and swelling throughout her body, fever. the doctor said it was toxic something but I want to research it more. He said she has a lot of inflammation and put her on Ibuprofen 3 x a day for 2 weeks. He said it was a virus. Then he called back to say if she starts bruising easily to take her to ER. Any ideas?