hmm that time when i breastfeeding my ger also got is it kinda bubble stuff?
when i asked the lactation lady she sae is becus never latch baby properly thus the blister on the nipple.
you can buy the nipple guard while breastfeeding to prevent such blisters in future =D
but i think if can you let your breast rest for few hours than later than feed but it will be very painful for the starting of the latch on. endure than little while ok =D
if prob;em still persists, you go see doc =D