It seems that you are having some bullous dermatosis
It is relapsing and bullae seem hard and remain for long time.
It may be bullous pemphigoid
or aquired epidermolytic bullosa.
You consult dermatologist
for firm diagnosis and treatment.
Thorough history ,keen clinical examination and investigations are needed to reach to the diagnosis.
DM,HIV and other internal diseases are to be ruled out.
Antibiotics,dapsone and steroids
may be helpful to control the dieases.
I hope you got my answer.
Dr. Ilyas Patel MD