What Causes Pain In The Mouth While Suffering From Fever?

My daughter is 11 and had a fever of 101.9 Wednesday night I gave her ibuprofen and it brought fever down. Next morning complained of mouth hurting so I took her to dentist. I thought she might have an infected tooth. Dentist said no and also cleaned her teeth and put fluoride on her teeth. She did not have a fever while in office. She brushed the fluoride off 3 or 4 hours later and then started to develop canker sores and little enflamed bumps on the outside edges of tongue. Fever came back at 101.4 gave her more ibuprofen which brought fever down. She woke up with the sores and fever again. Took her to dr at 3:00. They said it must be something viral. Did not look like strep or hand foot mouth disease. Gave no prescription. Next days fever but very sore mouth. Sunday no fever til 3:00 it was 100.9 mouth really sore. SHE WOULD NOT Hardly eat on SATURDAY OR SUNDAY BECAUSE OF THE pain. Has been drinking smoothies a little bit and ate meat off of jimmy johns sub this afternoon. Mouth in so much pain she doesn't want to even drink much water. What should I do..