The blisters on her tongue may be due to oral allergy
to the citrus fruits or might be due to the virus as such.
If she has such allergies- its better to inform everyone who ever takes care of her- as allergy can cause life threatening manifestations.
You may see your Pediatrician
for her oral lesions. Till then you may apply oral analgesic
gels like Zytee- that will reduce the pain and ease consumption of food.
Give her plenty of fluids/ bland food/ curd in plenty.
Wish your daughter good health.