Suggest Treatment For Mouth Blisters Along With High Fever During Pregnancy

My granddaughter will have her first baby in May. This past week she has gone to emergency ward becaat use of high fevers. One day it was 109. They sent her hdrinkome after looking at her and told her to take Tylenol. That's it. 3 trips back to emergency and there is still no help. Her mouth, tongue and throat is full of blisters.
She can't eat and can barely drink. Any help?