Hello I have had trouble with a bleb - a littl...

Hello I have had trouble with a bleb - a little blister on my nipple for about a month. The MCHN said to pop it with a sterilised needle, which I have been doing every 4-5 days for the last month. THe ABA had no real advice on it and I have left a message with the DR at the breastfeeding support service at the hospital, but she /he hasn't rung back yet. has anyone had one and how did they deal with it? Thanks