Hi. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain your granddaughter is suffering from PRIMARY HERPATIC GINGIVOSTOMATITIS which is a viral infection caused by Herpes Simplex Virus and leads to fever,irritability and swollen gums as well as formation of blisters in mouth and gums but fever and swollen gums mostly preceed the formation of blisters.. The treatment is symptomatic and antibiotics are not needed as they can only cure bacterial infection.. For fever you can give her Acetaminophen [Tylenol or Paracetamol].. For swollen gums you can apply cool packs as it will reduce inflammation and swelling.. In case of blister formation coating them with an antiviral ointment like Acyclovir and a numbing agent can relieve.. Antiviral drugs like Acyclovir,Valacyclovir can be given if the blisters outbreak to reduce the duration of sickness.. Give him a cool and bland diet, bread socket in milk, gelatin, and other soft foods and more of liquids should be given.. Maintain her oral hygiene by brushing her teeth with an ultrasoft toothbrush.. Provide her ample of rest.. In case if the symptoms does not resolve consult a Paediatrician and get her evaluated.. Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..