Hi. My 20month old developed a fever or 39 degrees 3 days ago at the nursery.. She also helped brush her teeth that morning. When I picked her up I noticed the gum aroound her upper front teeth were swollen and sore. That night I started her on Hibiotic .Yesterday night her left cheek was swollen and she still had a fever. She took her MMR shot at 14 months. What can this be?