hello, As per ur description it seems u r having draining abscess/sinus
.. the blister
is opening of infection from either soft tissues (gingiva
, periodontal ligament) or from hard tissues ( bone,tooth)
It has to be assesed clinically and radiographically about the origin of abscess..
most commonly it is from carious or traumatised tooth.. and to treat it permanently RCT of involved tooth is done.and blister resolves forever..
if its from gums only..then gums /periodontal surgery is done..to treat it..
meanwhile u can use chlorhexidine
mouthwash/ gels on ur gums temporarily..