hello dear, its really a surprising condition , bubbles in scar area !! well as per your history what i can suspect that it is an endogenous eczema
. u can use calasoft lotion to get some relief. also some antihistamine will be good.
also i doubt it may be any of autoimmune disorder, so i suggest u to meet a dermatologist
. he ll examine the fluid from the lesion and also ll do a biopsy
if needed. please visit when lesions are fresh. hope u get well soon. thank u