Your child may be having bullous dermatosis
... Probably chronic bullous dermatosis of childhood or linear IgA dermatosis. Or it may be some other disease like epidermolysis bullosa
. It is difficult to clinch the diagnosis with this much history and without clinical examination. I would like to recommend to consult nearby eminent dermatologist
. He will examin your child. He may suggest some investigations.And will prescribe proper medicines. I hope you got my answer.
Dr. Ilyas Patel MD