Thanks for writing here.
Blister associated with fever probably suggest chicken pox
.Intially there are only 1 to 2 blisters but they can spread all over body.It is always better to take antiviral
course like acyclovir
or valacyclovir.You may apply a topical antiboitic like t bact cream over affected area.It will be better to take these drugs under the guidance of a dermatologist
Hope this will help you.Take care.